The Coastal Zone

Question 0

Why do waves break?

Answer 0

Start out as circular orbit, friction slows orbit as wave nears shore, orbit becomes elliptical, top of orbit breaks over and wave washes up shore.

Question 1

What 2 main things shape the coastline?

Answer 1

Waves/erosion and weathering.

Question 2

What is swash and backwash?

Answer 2

Swash is when waves wash up onto beach (at angle because it’s controlled by wind).
Backwash is when waves wash back out to sea (always at right angles to beach).

Question 3

What is fetch?

Answer 3

The distance over which the wind has blown.

Question 4

What are the characteristics of a constructive wave?

Answer 4

Powerful with strong swash and weak backwash. Low frequency. Adds material to beach.

Question 5

What are the characteristics of a destructive wave?

Answer 5

Formed by storm with strong backwash and weak swash. High frequency. Removes material from beach.

Question 6

Name the 4 types of mass movement.

Answer 6

Rockfall, landslide, mudflow and rotational slip.

Question 7

What is cliff collapse?

Answer 7

When steeply sloping parts of cliff fall onto beach below.

Question 8

Name the 4 erosion processes.

Answer 8

Hydraulic power, corrasion, solution and attrition.

Question 9

What is hydraulic power?

Answer 9

The force of waves smashing on a cliff. Water gets in cracks so they expand and break the rock.

Question 10

What is corrasion?

Answer 10

Rocks being flung at cliff by powerful waves that scrape and ‘sandpaper’ the cliff.

Question 11

What is solution?

Answer 11

The dissolving of rocks like limestone and chalk.

Question 12

What is attrition?

Answer 12

The knocking together of rocks, making them smaller and smoother.

Question 13

What is coastal transportation and the 4 processes?

Answer 13

Sediment being moved by the sea. Traction, saltation, suspension and deposition (and solution).

Question 14

What is traction?

Answer 14

Large, heavy pebbles rolled along seabed.

Question 15

What is saltation?

Answer 15

‘Hopping’ of pebbles too light for traction and too heavy for suspension.

Question 16

What is suspension?

Answer 16

Rocks carried within the water.

Question 17

What is deposition?

Answer 17

When sediment is dropped after the flow of water slows down.

Question 18

What is longshore drift?

Answer 18

The transportation and deposition of sediment up and down a beach caused by waves approaching at angle. Zig zag movement. Mostly occurs in bays where there’s decrease in wave energy.

Question 19

Name the 9 erosion landforms.

Answer 19

Arch, cave, cliff, stack & stump, bay & headland and wave cut notch & wave cut platform.

Question 20

How are arches formed?

Answer 20

Waves cut through side of headland to form the arch shape.

Question 21

How are caves formed?

Answer 21

Corrasion and hydraulic power widens the cliff to form the hollow space.

Question 22

How are stacks and stumps formed?

Answer 22

Roof of arch collapses to leave isolated pinnacle of rock which is a stack. When stack collapses, it leaves a stump.

Question 23

How are bays and headlands formed?

Answer 23

Cliffs have alternating hard and soft rock. Soft rock (sand/clay) eroded by hydraulic power or abrasion creates inlet bay where longshore drift is due to weaker waves. Hard rock (chalk/limestone) stays as section jutting out into sea.

Question 24

How are wave cut notches and platforms formed?

Answer 24

Cliff erosion at high tide creates small indent in cliff. Notch gets bigger over time until it collapses. This process of collapsing wave cut notches will eventually retreat cliff to make gently sloping platform at cliff base.

Question 25

Name the 3 deposition landforms.

Answer 25

Spits, bars and beaches.

Question 26

What is a spit and its formation?

Answer 26

Finger of sand/shingle jutting out into sea. Sediment form longshore drift deposited where coast changes direction or has river mouth. After more deposition, sediment extends away from coast and breaks surface. Waves approaching from new directions makes spit curved and grass etc will grow. Where water is calm, there’ll be salt marshes.

Question 27

What is a bar?

Answer 27

A spit that has grown across a bay, trapping a freshwater lake/lagoon behind it.

Question 28

What is a beach and its formation?

Answer 28

Deposit of sand at coast. Sediment transported and deposited by constructive waves that shape a bay. Wind pushes sediment inland and sand is moved by saltation/suspension. Small particles at foreshore, large at back. Build up of this deposition shapes beach.

Question 29

Outline the Happisburgh case study.

Answer 29

Village on North Sea coast of East Anglia. Sea level rise w/ destructive waves –> Erosion of cliff edge. Tried managed retreat but homeowners forced to leave.

Question 30

What are 3 economic impacts of sea level rise and 3 environmental?

Answer 30

Economic: expensive coastal defences, loss of farmland, compensation for homeowners.
Environmental: destroys salt marshes, flooding, loss of sand dunes.

Question 31

What is hard engineering and the 4 defences?

Answer 31

Using artificial structures to control coast. Sea wall, revetments, rock armour and groynes.

Question 32

What is soft engineering and the 3 methods?

Answer 32

Managing coast without built structures. Beach nourishment, dune regeneration and managed retreat.

Question 33

What are sea walls?

Answer 33

Concrete barrier with curved face to reflect waves back to sea, placed at foot of cliff or top of beach.

Question 34

What are revetments?

Answer 34

Sloping structures that break up wave energy.

Question 35

What is rock armour?

Answer 35

Piles of boulders at foot of cliff that break waves and absorb the energy.

Question 36

What are groynes?

Answer 36

Rock structures that vertically line from coast to the sea to trap sediment from longshore drift, enlarging the beach.

Question 37

What is beach nourishment?

Answer 37

Addition of sand to the beach to make it higher/wider.

Question 38

What is dune regeneration?

Answer 38

Dunes planted as buffers to sea yet easily trampled on.

Question 39

What is managed retreat?

Answer 39

Allowing low lying coastal areas to be flooded into salt marshes because salt marshes are good barriers to sea.