Weathering

Question 1

Erosion

Answer 1

Break down of rocks by moving agents that transport material away

(Sea/river/wind)

Question 2

Freeze thaw (physical)

Answer 2

1. Water enters cracks
2. Temp falls (night) water freezes + expands (9% in volume)
3. Pressure on rock
4. Temp rises (day) melts + takes up less room
5. More water enters, repeated, weakens, rock breaks into pieces

High rain, fluctuating temp +/- freezing

Question 3

Exfoliation

Answer 3

1. Hot (day) surface expands
2. Cool (night) surface contracts
3. Repeated, stress, weakens rock
4. Outer layer breaks off, process again on layers underneath

High day temp, low night temp

Question 4

Carbonation

Answer 4

1. Rainwater combines with CO2 to form carbonic acid
2. Attacks surface + soaks in joints
3. Reacts with alkaline limestone to form calcium bicarbonate
4. Carried away in solution (soluble)

High rain, high temp (doubles with 10°C rise)

Question 5

Oxidation

Answer 5

1. Oxygen (air) reacts with minerals (metal) in rock - iron
2. Changes structure: expands + weakens rock
3. Breaks down easily - rust
4. Red brown colour, rock crumbles easily

High rain, high temp (doubles with 10°C rise)

Question 6

Plants

Answer 6

1. Roots move along crack + force apart rock
2. Widen, weaken + disintegrate (mechanical)
3. Release chemicals: carbonic acid (chemical)

High temps (summer) for growth and chemicals

Question 7

Animals

Answer 7

1. Burrow in rock, weakens + breaks down (mechanical)

2. Die, decompose, release chemicals (chemical)

Question 8

Factors influencing type + rate of weathering

Answer 8

Many minerals, oxygen and water - CHEMICAL
Lines of weakness (bedding planes and cracks) - MORE LIKELY
Coarse grain (sandstone) - QUICKER than fine
Climatic conditions

Question 9

Weathering rapid in humid tropical areas

Answer 9

Higher temp/rain (chemical) 
More trees/roots (biological) 
More animals (biological) 
More cracks (physical) 
Rapid decay (chemical) 
CO2 from decay - acidic rain (chemical) 
Rate doubles with 10°C rise (chemical)

Question 10

Opportunities of natural environment (weathering)

Answer 10

Agriculture 
Tourism (rock climbing) 
Building (limestone, cement) 
Education 
Forestry

Question 11

Weather and climate

Answer 11

Weather: day to day changes of earth’s atmosphere

Climate: average weather over period of time

Question 12

Features of Stevenson screen

Answer 12

1.25m above ground - air temp
White - reflect sunlight
Downwards slats - air passes freely, wind doesn’t affect readings
Away from buildings - no effect of local relief
Grass - concrete absorbs heat

Max min thermometer, wet dry bulb thermometer + barometer

Question 13

Rain gauge (precipitation)

Answer 13

Grass - avoid splashback
No trees/buildings - avoid shelter/water dripping

Remove bottle, empty into measuring cylinder, read at eye level
Every 2 hours/same time

Question 14

Max min thermometer (highest/lowest temp)

Answer 14

Alcohol expands/contracts, affects mercury, pushes steel markers

Read lower end of index, work out difference, eye level
Reset with magnet

Diurnal temp range: highest - lowest

Question 15

Wet + dry bulb thermometer (relative humidity)

Answer 15

Greater difference, less water vapour in air, drier air, lower relative humidity

Records air AND air as if 100% saturated (damp)
Read relative humidity off table

Question 16

Barometer (air pressure, mb)

Answer 16

Pressure moves pointer around dial
High pressure on glass moves dial to high
Low pressure, moves to low

Question 17

Wind vane (direction)

Answer 17

Record once an hour (changes frequently)

Arrow points in direction wind blows from

Question 18

Anemometer (wind speed)

Answer 18

Cups rotate by air movement
Number of revolutions recorded on meter + automatically converted to km/h

Or Beaufont scale

Question 19

Wind rose

Answer 19

Shows direction, frequency + strength (in month)

Strength = length of arm to centre 
Frequency = width of arm

Question 20

Clouds and types

Answer 20

Visible mass of water droplets suspended in atmosphere
Air cools, condenses + can’t absorb any more water

Cumulus: heaped, bubbly, high tops
Stratus: sheet/layer
Cirrus: wispy, high altitude
Nimbus: rain bearer, grey/low

Estimate eights of cover by eye, less precise, shade circle segments

Question 21

Convectional rainfall (cumulonimbus)

Answer 21

1. Shortwave radiation from sun heats ground
2. Long wavelength heats air above
3. Transpiration + evaporation
4. Air rises (humid)
5. Cools + condenses (clouds)
6. Water particles collide and get heavier, saturated, fall as rain
7. Repeats

Question 22

Weathering

Answer 22

Breakdown of rock by mechanical/physical/biological forces insitu (not removed)