COASTS

Question 1

What is solution?

Answer 1

When the water dissolves certain types of rocks, eg limestone.

Question 2

What is abrasion?

Answer 2

When pebbles grind along the river bank and bed in a sand-papering effect.

Question 3

What is hydraulic action?

Answer 3

Water smashes against the river banks. Air becomes trapped in the cracks of the river bank and bed, and causes the rock to break apart.

Question 4

What is attrition?

Answer 4

When rocks that the river is carrying knock against each other. They break apart to become smaller and more rounded.

Question 5

What are constructive waves?

Answer 5

Constructive waves are low energy and have stronger swashes than backwashes. They build up beaches.

Question 6

What are destructive waves?

Answer 6

Destructive waves have stronger backwashes than swashes. They take away sediment from beaches.

Question 7

What is freeze-thaw weathering?

Answer 7

When water continually seeps into cracks, freezes and expands, eventually breaking the rock apart.

Question 8

What is chemical weathering?

Answer 8

Chemical weathering occurs when water dissolves minerals in a rock, producing new compounds. This changes the molecular structure of rocks and soil.

Question 9

What is biological weathering?

Answer 9

Biological weathering occurs when plants break up rocks with roots or root exudates.

Question 10

What is rockfall (mass movement)?

Answer 10

Bits of rock fall off the cliff face, usually due to freeze-thaw weathering.

Question 11

What is mudflow (mass movement)?

Answer 11

Saturated soil (soil filled with water) flows down a slope.

Question 12

What are landslides (mass movement)?

Answer 12

Large blocks of rock slide downhill.

Question 13

What is rotational slip (mass movement)?

Answer 13

Saturated soil slumps down a curved surface.

Question 14

Give examples of hard engineering on coasts.

Answer 14

Sea walls.
Rock armour.
Gabions.
Groynes.

Question 15

What do sea walls do?

Answer 15

Concrete walls that are placed at the foot of a cliff to prevent erosion. They are curved to reflect the energy back into the sea.
Expensive and still can be eroded!!

Question 16

What does rock armour do?

Answer 16

Large boulders placed at the foot of a cliff. They break the waves and absorb their energy.
Rocks are expensive and do not blend in!!

Question 17

What do gabions do?

Answer 17

Rocks are held in mesh cages and placed in areas affected by erosion.
Not very strong and looks unnatural!!

Question 18

What do groynes do?

Answer 18

Wooden or rock structures built out at right angles into the sea.
By trapping sediment it starves beaches further down the coastline and they look unattractive!!

Question 19

Give examples of soft engineering on coasts.

Answer 19

Beach nourishment.
Reprofiling.
Dune nourishment.

Question 20

What does beach nourishment do?

Answer 20

Sand is pumped onto an existing beach to build it up.
Needs to be constantly replaced and the sand has to be brought in from elsewhere!!

Question 21

What does reprofiling do?

Answer 21

The sediment is redistributed from the lower part of the beach to the upper part of the beach.
Only works when wave energy is low and needs to be repeated continuously!!

Question 22

What does dune nourishment do?

Answer 22

Marram grass planted on sand dunes stabilises the dunes and helps to trap sand to build them up.
Can be damaged by storm waves and areas have to be zoned off from the public, which is unpopular!!

Question 23

Jurassic coast case study.

Answer 23

Old Harrys rocks.
Cave –> arch –> stack –> stump

Question 24

How are caves arches stacks and stumps formed?

Answer 24

Caves occur when waves force their way into cracks in the cliff face. This is hydraulic action.
If the cave is formed in a headland, it may eventually break through to the other side forming an arch.
The arch will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.
The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump.

Question 25

What is a concordant coastline?

Answer 25

A concordant coastline has the same type of rock along its exposed length.

Question 26

What is a discordant coastlines?

Answer 26

Coastlines where the geology alternates between blocks of hard rock and soft rock.

Question 27

What is long shore drift?

Answer 27

Swash pushes sediment up the beach in the direction of the waves (prevailing wind)
The backwash then carries material down the beach at right angles back towards the sea

Question 28

What is traction?

Answer 28

Large particles like boulders are pushed along the sea bed

Question 29

What is saltation?

Answer 29

Pebble-sized particles bounced along the sea bed

Question 30

What is suspension?

Answer 30

Small particles like silt and clay are carried along in the water

Question 31

What is solution (transportation)?

Answer 31

Soluble materials dissolved in the water and carried along

Question 32

What causes deposition?

Answer 32

When water carrying sediment loses energy and slows down

Question 33

How are beaches formed?

Answer 33

By constructive waves depositing material

Question 34

How are spits formed?

Answer 34

Longshore drift transports sand and shingle past the sharp bend in a coastline and deposits it in the sea

Question 35

How do bars form?

Answer 35

When a spit joins two headlands together

Question 36

How do sand dunes form?

Answer 36

When sand deposited by long shore drift is moved up the beach by wind
Obstacles (driftwood) cause wind speed to decrease so sand is deposited
Roots of vegetation stabilise the sand
Embryo —> foredune —> mature

Question 37

What is an example of a cove?

Answer 37

Lulworth cove in Dorset