Coasts, 10

Question 1

Destructive waves

Answer 1

• they are created in storm conditions.
• they are also created from big , strong waves when the wind is powerful.
• they occurs when wave energy is high and the wave has travelled over a long fetch

Question 1

Swash of the wave

Answer 1

Swash goes up at the angle of the wind ( on the direction of the wind ).

Question 2

Wave

Answer 2

A wave is a body of water moving towards a coastline at higher than average level.

Question 3

Backwash of the wave

Answer 3

The backwash is always at right angles to the sea.

Question 4

Constructive waves

Answer 4

• they are created in calm weather and are less powerful than destructive waves.
• they break on the share and deposit material, building up reaches.
• they have a Swash that is stronger than the backwash.

Question 5

Formation of wave cut platform

Answer 5

1. Erosion occurs at high water / high tide.
2. The processes of erosion must be mentioned ie. Corrasion, solution and hydraulic action.
3. Undercutting occurs.
4. A wave cut notch is formed at the base of the cliff.
5. The resulting overhang collapses and the cliff.
6. A large area of flat rock is left at the base of the new cliff line. This is the wave-cut platform.

Question 6

Caves, Arches and stacks

Answer 6

1. CRACK
   a large crack is enlarged by the pressure on / off effect of hydraulic action.
2. NOTCH
   the crack grows into a notch and then a cave as destructive waves coverage on the headland and continue to erode it.
3. CAVE
   over time, the cave becomes larger. Wave refraction draws waves to all sides of the headland so caves may form back-to-back.
4. ARCH
   the sea breaks through the back of the cave forming a natural arch is widened as notches form.
5. HEAVY TOP OF THE ARCH
   weathering such as freeze-throw continues to weaken the top of the arch, making it
   less stable.
6. ROCKS FELL
   top of the arch eventually collapses.
7. STACK
   this leaves a pillar of detached rock called a stock.
8. STACK STARTS TO FALL
   notches from at the base of the stack, which eventually makes it unstable.
9. STUMP
   the stack will eventually topple into the sea, leaving only its base. This stump is normally only visible at low tide.

Question 7

Transportation and LSD( long shore drift ),
Solution

Answer 7

Solution = dissolved chemicals ( often derived from chalk or limestone) in sea water and carried in solution. The load is not visible.

Question 8

Transportation and LSD( long shore drift), suspension

Answer 8

Suspension = small particles are carried (suspended) in water, eg slits and clays, which can make the water look cloudy.

Question 9

Transportation and LSD( long shore drift ), saltation

Answer 9

Saltation = load is bouncing or hopping along the sea bed, eg small pieces of shingle or large sand grains. Particles which are too heavy to be suspended.

Question 10

Transportation and LSD( long shore drift ), traction

Answer 10

Traction = pebbles and larger sediment are rolled along the sea bed.

Question 11

Long shore drift

Answer 11

Long shore drift = transport of sediment along a stretch of coastline caused by waves approaching the beach at an angle.

Question 12

The land forms, types (3)

Answer 12

1. Beaches
2. Splits
3. Bars

Question 13

Coastal deposition.
Deposition is likely to occur when:

Answer 13

• waves enter an area of shallow water.
• waves enter a shelter area, eg a cove or bay, where low energy means constructive waves are dominant.
• there is little wind.
• wide expanse of flat beach, so swash spreads out, weaking the wave, so backwash is weak.
• there is a good supply of material from up drift erosion.

Question 14

Beach

Answer 14

A beach is the gently sloping area of land between the right and low water marks.

Beaches ARE NOT permanent features as their shapes are alternated by waves.

Question 15

Split

Answer 15

A split is a narrow coastal land formation that is tied to the coast at one end

Question 16

Formation of Bar

Answer 16

Because of wind creates long shore drift and sand bank is carrying on the beach. At the end of it, it starts deposition and split forms. Split joins with headlands and creating the bar behaving and it creates lagoon.

Question 17

Formation of Tombolo

Answer 17

Tombolos are formed where a split continues to grow outwards joining land to an offshore island to be located in the path of the land of the long shore drift for the split to latch onto as it grows.
Tombolos, like all deposition features can be removed during large storm but are often permanent and used.

Question 18

Location of Dune

Answer 18

Essential conditions, large flat beach, large supply of sand, onshore wind, large tidal range and an obstacle such as drift wood.

Question 18

Similarities and differences between the bars and splits.

Answer 18

Similarities: they creating in the same way( long shore drift)
Differences: bars going to lagoon, split goes to the sea.

Question 19

Sand dunes

Answer 19

Sand dunes are often found at the back of a beach. However, they need very specific contact to form and are therefore not uniformly seen

Question 20

Sand movement

Answer 20

Sand movement = the sand used to create dunes is transported to the back of the beach by the wind in 3 main ways, creep, saltation, suspension

Question 21

Formation of dune

Answer 21

1. At the back of the beach is an obstacle such as drift wood.
2. Heaviest grains settle against the obstacle, lighter ones settle on other side of obstacle.
3. Side facing the wind begins to form a crest.
4. This is because the pile of sand become too steep to build ups and falls under its own weight .
5. Sand stops slipping when slope reaches a gradient of 30-34 degrees.
6. Repeated movement of material up windward side and down leeward side causes dunes to migrate inland.
7. Sand dune its self becomes and obstacle and other dunes from in front of it.

Question 22

Concordant

Answer 22

Concordant = where bands of different rock type run parallel to the coastline.

Question 23

Discordant

Answer 23

Discordant = layers of rock at right angles to the coast.

Question 24

Hard engineering

Answer 24

Hard engineering = building artificial structures aimed at controlling natural process.

Question 25

Hard engineering, gabions

Answer 25

What is it?
A wall of wire cages filled with rocks, usually built at the foot of cliffs.

Benefits
Gabions absorb wave energy and so reduce erosion. They’re cheap and easy to build.

Costs
They’re ugly to look at and the wire cages can corrode over time.

Question 25

Hard engineering, sea wall

Answer 25

What is it?
A wall made out of a hard material like concrete that reflects waves back to sea.

Benefits
It prevents erosion of the coast. It also acts as a barrier to prevent flooding.

Costs
It creates a strong backwash that erodes under the wall. Expensive to build and maintain

Question 25

Soft engineering

Answer 25

Soft engineering = a sustainable approach to managing the coast without using artificial structures.

Question 25

Hard engineering, groynes

Answer 25

What is it?
Wooden or stone fences that are built at right angles to the coast. They trap material transported by long shore drift.

Benefits
They create winder beaches which slow the waves. This gives greater protection from flooding and erosion. They’re a fairly cheap defence.

Costs
They starve beaches further down the coast of sand, making them narrower. Narrow beaches don’t protect the coast as well, leading to greater erosion.

Question 25

Soft engineering, beach nourishment and reprofiling

Answer 25

What is it?
Sand and shingle from elsewhere (e.g. from the seabed) or from lower down the beach that’s added to the upper part of beaches.

Benefits
It creates wider beaches which slow the waves. This gives greater protection from flooding and erosion.

Costs
Taking material from the seabed can kill organisms like sponges and corals. It’s a very expensive defence. It has to be repeated.

Question 25

Hard engineering, rock armour

Answer 25

What is it?
Boulders that are piled up along the coast

Benefits
It absorb wave energy, reducing erosion and flooding. It’s a fairy cheap defence.

Costs
Boulders can be moved around by strong waves, so they need to be replaced.

Question 26

Soft engineering, dune regeneration

Answer 26

What is it?
Creating or restoring sand dunes by nourishment, or by planting vegetation to stabilise the sand

Benefits
Dunes create a barrier between land and sea and absorb wave energy, preventing flooding and erosion. Stabilisation is cheap.

Costs
The protection is limited to small area. Nourishment is very expensive.

Question 27

Mass movement

Answer 27

Mass movement = is the shifting of rock sand loose material down a slope, eg a cliff. It happens when force of gravity acting on a slope is greater then the force supporting it.