Enquiry Question 2

Question 1

What rocks do hard rock coasts consist of?

Answer 1

Resistant rock such as igneous granite, and resistant sedimentary rock such as sandstone, limestone or chalk.

Question 2

What rock does soft rock coasts consist of?

Answer 2

Less resistant rock such as clays and shales.

Question 3

What are two weaknesses in rock structure?

Answer 3

Joints and Faults

Question 4

What are joints?

Answer 4

Joints are small, usually vertical, cracks found in many rocks

Question 5

What are faults?

Answer 5

Faults are larger cracks caused by past tectonic movements, where rocks have moved

Question 6

What are types of rock structure?

Answer 6

Discordant and concordant

Question 7

What is a discordant coast

Answer 7

When the strata are at right angles to the coast. These have different type of rock.

Question 8

What is a concordant coast?

Answer 8

If the strata is parallel to the coastline

Question 9

What does discordant coats create?

Answer 9

They create headlands and bays from the different resistances of rock.

Question 10

What do concordant coasts create?

Answer 10

They create coves and cliffs from erosion eroding one part of the coast and then reaching weaker rock behind.

Question 11

What is hydraulic action?

Answer 11

When water is forced into cracks in rocks, the air is compressed. When the wave retreats the compressed air blasts out, forcing rocks apart.

Question 12

What is abrasion?

Answer 12

When loose sediment are thrown against the cliff by waves. This chips bits of rock of the cliff.

Question 13

What is attrition?

Answer 13

When loose sediment is swirled around at the bottom of the sea by waves. The sediment constantly collides together and gradually gets worn down into smaller sediment.

Question 14

What is solution?

Answer 14

When the sea becomes very slightly acidic. This dissolves rocks such as chalk and limestone.

Question 15

What is coastal erosion?

Answer 15

Coastal erosion is the breakdown and removal of sediment at the coastline caused by the waves.

Question 16

What affects the size of waves?

Answer 16

The wind power and wind direction. The fetch or the area of sea where the waves can grow in power.

Question 17

Where are the most powerful waves in the UK?

Answer 17

The most powerful waves in the UK are found on the west coast of the UK and Ireland because of the 6000km fetch and winds of 12m/s.

Question 18

What are the features of destructive waves?

Answer 18

They remove sediment from the beach. They have a short wavelength and steep gradient. A small swash but strong backwash that erodes the beach.

Question 19

What are the features of constructive waves?

Answer 19

They add sediment to the beach. They have a long wavelength but small gradient. A strong swash but weak backwash.

Question 20

What are sub aerial processes?

Answer 20

Sub aerial processes are changes that take place on the land itself. The main type is weathering.

Question 21

What is two examples of mass movement?

Answer 21

Rotational slumping

Rock slides

Question 22

What is rotational slumping?

Answer 22

Clay is impermeable and prevents water moving through it
Sand is permeable and allows water to pass through
Rain falls and it accumulates at the boundary between sand and clay which lubricates the boundary
The sand becomes saturated and will dramatically slump rotationally

Question 23

What is rock slides?

Answer 23

Joints or bedding planes are aligned diagonally to the sea. Erosion at the base, or weathering at the top of the cliff. The cliff becomes unsupported and sometimes lubricated by rain. It moves in a straight diagonal line.

Question 24

How are headlands and bays formed?

Answer 24

Headlands and bays form on a discordant coastline where the less resistant rock is eroded much faster to create bays and the resistant rock is eroded slowly. Wave refraction will now redirect most of the waves energy on the headland so the bays will be sheltered and experience deposition. The headland will be eroded and form cliffs.

Question 25

How are wave cut platforms formed?

Answer 25

The wave erodes the cliff between low and high tide - inter tidal zone. This creates a wave cut notch. Then erosion means the rock above the notch is unsupported and collapses leaving a gently sloping rocky platform.

Question 26

How is a stump formed?

Answer 26

1. A weakness occurs in the headland in the form of a crack or fault.
2. The waves erode the base of the crack which forms a cave.
3. The back of the cave is eroded to create an arch.
4. The base of the arch is eroded to create a wave cut notch leaving the rock above unsupported so it collapses.
5. The roof of the arch is eroded by chemical and biological processes and the arch becomes wider until the roof collapses.
6. This leaves a stack.
7. The base of the stack is eroded to create a wave cut notch, the rock above collapses leaving a stump.

Question 27

What is longshore drift?

Answer 27

The waves enter the beach in the direction of the strong prevailing wind. The swash is strong and the backwash is weak so the waves deposited material. This process continues so that sediment is transported in the direction of the wind.

Question 28

How is a beach formed?

Answer 28

The energy from waves are mainly absorbed by headlands where sediment is eroded. This sediment is then deposited on the beach by constructive waves and long shore drift.

Question 29

How is a spit formed?

Answer 29

Longshore drift moves sediment along the coastline.
A sudden change in the coastline is needed for a spit to occur.
Behind a headland there is a sheltered area where deposition occurs.
The heaviest largest material is dropped first by the headland.
Gradually smaller sediment is dropped and the spit grows.
A secondary wind direction creates a secondary long shore drift direction to create a recurred end to the spit.
Waves don’t reach behind the spit so water calmer and deposition creates salt marshes.
The spit won’t reach all the way across the bay because of the deep water and river currents.

Question 30

How is a bar formed?

Answer 30

A bar is formed when a spit encounters no change in wind direction or movement of water so it grows until it reaches the other headland of the bay forming a bar and a lagoon behind it.

Question 31

Where is Swanage?

Answer 31

Swanage is in the south of the U.K. on the coast. It is south of Bournemouth and has 3 bays and 2 headlands.

Question 32

How has human activity influenced the Swanage coast?

Answer 32

About half of Swanage bay is built up and defended because of tourism. Sea defences include groynes and a sea wall. North of Swanage to Ballard point and the Foreland the beach gives way to limestone cliffs because no sediment is being transported their as it is all kept at the south of Swanage bay.

Question 33

Where is Swanage?

Answer 33

Swanage is in the south of the UK on the coast. It is south of Bournemouth and has 3 bays and 2 headlands. Swanage bay is to the east of Swanage and north of Durlston head.

Question 34

How may settlements be affected by coastal erosion?

Answer 34

Over 20million people live within the coastal zone. At Holderness for example, over 29 villages have been lost to coastal erosion in the last 1000years.

Question 35

How has tourism affected coastal erosion?

Answer 35

Structures like groynes are built to trap sand on and protect tourist beaches. However removing sediment from the system results in increased erosion further along the coast.

Question 36

How may coastal erosion impact infrastructure?

Answer 36

Roads, railways, oil refineries, chemical plants and ferry and shipping ports are located along the coast. The ESSO oil refinery at Fawley near Southampton is the largest in the U.K. It handles over 2000 ships a year, transporting 22 million tonnes of crude oil. Large cities and industrial areas have high economic value and are often protected with hard engineering.

Question 37

How has construction affected coastal erosion?

Answer 37

In 1897 over 600,000 tonnes of gravel were dredged from the sea bed to build Plymouth Docks in Devon. Soon after wave action eroded the 5metre high wall that was protecting nearby Hallsands village, which was then destroyed by storms in 1917.

Question 38

How may agriculture be affected by coastal erosion?

Answer 38

Sea level rise and erosion is already leading to the loss of agricultural land and could affect the fishing industry in area such as the Exe estuary in Devon. Land used for agriculture has a low economic value and isn’t protected.