Coasts KQ2- formation of landforms

Question 1

Describe what a wave cut platform is

Answer 1

A flat, gently sloping horizontal areas of rock found at the base of cliffs

Question 2

Describe what a cliff is

Answer 2

Near vertical faces of exposed rock, where the sea meets the land

Question 3

Give an example of an area where cliffs and wave cut platforms are found

Answer 3

Broad bench, Kimmeridge, Dorset

Question 4

Outline how wave cut platforms are formed

Answer 4

• waves erode the base of a cliff by abrasion, hydraulic action, pounding
• This leads to undercuttin and formation of a wave-cut notch
• Eventually unsupported rock collapses
• The collapsed cliff material is washed away by waves
• Cliffs retreat as this occurs repeatedly

Question 5

Describe what a wave-cut notch is

Answer 5

A small indent at the base of a cliff

Question 6

Describe what bays are

Answer 6

bodies of water which are surrounded by land on three sides

Question 7

Define weathering

Answer 7

The in-situ disintegration of rock by chemical, biological, and physical processes

Question 8

How does physical weathering allow other weathering to take place?

Answer 8

Physical weathering breals rock into smaller pieces, which increases the surface area for other weathering to take place

Question 9

Give 4 examples of physical weathering

Answer 9

• Freeze-thaw weathering
• Pressure release
• Thermal expansion
• Salt crystalisation

Question 10

Describe the process of freeze-thaw weathering

Answer 10

• water enters cracks and freezes
• when water freezes it expands
• expansion of water causes pressure on rocks
• this can split even resistant rock and cause pieces to break off

Question 11

Describe the process of pressure release weathering

Answer 11

• Overlying rocks are removed by weathering and erosion releasing pressure on rock
• Underlying rock expands and fractures
• Causing parallel fractures to form

Question 12

Describe the process of thermal expansion weathering

Answer 12

• Rocks experience repeated cycles of temperature change
• When rock is heated it expands, and when it is cooled it contracts
• This causes the outer layers of rock to crack and flake off

Question 13

Describe the process of salt crystallisation

Answer 13

• Salts precipitate and form crystals in pore spaces in rocks
• This causes pressure within the rock
• Causing rock to disintegrate

Question 14

Which salts are particuarly effective at salt crystallisation weathering?

Answer 14

Sodium sulfate and sodium carbonate

Question 15

What is chemical weathering?

Answer 15

Weathering which involves reactions between moisture and some minerals within the rock

Question 16

Name 5 examples of chemical weathering

Answer 16

• Oxidation
• Carbonation
• Solution
• Hydrolysis
• Hydration

Question 17

Describe the process of oxidation weathering

Answer 17

• Minerals in rock react with oxygen from air or water
• The original structure of the rock is destroyed and disintegrated

Question 18

Which type of rock is particularly susceptible to oxidation?

Answer 18

Sandstone- as it contains a high % of Iron

Question 19

Describe the process of carbonation

Answer 19

• Rainwater reacts with dissolved carbon dioxide to produce weak carbonic acid
• The carbonic acid reacts with calcium carbonate to produce calcium bicarbonate
• Calcium bicarbonate is soluble in water
• Rocks containing calcium carbonate are dissolved

Question 20

Describe the process of solution (as a weathering process)

Answer 20

• Some salts are soluble in water or in specific conditions
• Rock minerals dissolve, reducing the size of rocks
• The structural integrity of the rock can be undermined

Question 21

Describe the process of hydrolysis (weathering)

Answer 21

• Silicates combine with water, reacting chemically to produce clays
• The secondary minerals that are produced are much softer than the original rock
• The rock can be eroded more easily

Question 22

Describe the process of hydration (weathering)

Answer 22

• When water reacts with rocks new minerals are created
• The new minerals have a larger volume than the original rocks
• This causes pressure to be exerted
• Surface flaking of rock occurs

Question 23

What is biological weathering?

Answer 23

Weathering which may consist of physical or chemical processes but these are crucially as a result of the action of living organisms

Question 24

Give 2 examples of biological weathering

Answer 24

• Tree root weathering
• Organic acids/chelation

Question 25

Describe the process of tree root weathering

Answer 25

* Tree roots grow into cracks and exert pressure * If these trees topple they act as a lever * Pressure exerted on cracks can expand fissures in the rock * Trees toppling bring soils and rock to the surface allowing them to be weathered further

Question 26

Describe the process of chelation (weathering)

Answer 26

* Molluscs secrete acids * Decomposition of plant and animal litter can cause soil water to become acidic * Acidic soil reacts with some minerals * Molluscs cause small surface hollows in rock

Question 27

Define mass movement

Answer 27

The downslope transportation of material under gravity

Question 28

What are the factors that affect mass movement?

Answer 28

* amount of water * vegetation * marine processes/wave action

Question 29

What are the 3 categories that mass movements can be split into?

Answer 29

* Fast * Slow * Flow

Question 30

Give an example of flow mass movement

Answer 30

Mudflow

Question 31

Give 3 examples of fast mass movement

Answer 31

* Rock slide * Rock fall * Slumping

Question 32

Give 2 examples of slow mass movement

Answer 32

* Soil creep * Rain splash

Question 33

Describe the process of soil creep

Answer 33

* Individual soil particles are pushed down or heaved to the surface by wetting, heating, or freezing * Soil particles move at right angles to the surface * When dry soil particles move under the influence of gravity

Question 34

Describe the process of rain splash (mass movement)

Answer 34

When a raindrop falls on soil it dislodges soil particles

Question 35

Describe the process of mudflow

Answer 35

* Material on a slope becomes saturated with water, making it much heavier * Material moves down a slope in the form of a fluid * Most likely to occur after intense rainfall

Question 36

What geology makes a slope vulnerable to mudflow?

Answer 36

Thin soils overlying impermeable rock

Question 37

Describe the process of rock slides

Answer 37

* Rocks have jointing or bedding planes roughly parallel to the angle of the slope * Once weathered, large blocks of rock can slide downhill

Question 38

Describe the process of rockfalls

Answer 38

* Occur on slopes in excess of 40° * Can result from extreme physical or chemical weathering, storm action, or earthquakes * Bits of rock fall off the cliff face * Material that accumulates at the base is called tallus/scree

Question 39

Describe the process of rotational slumping

Answer 39

* Saturated soil slumps down a curved surface * Occur where weaker rocks/clays overlay more resistant or impermeable rock * Creates curved slip planes