Rocks and Weathering

Question 1

weathering

Answer 1

the decomposition and disintegration of rocks in situ

Question 2

decomposition

Answer 2

chemical weathering that creates altered rock substances

Question 3

disintegration

Answer 3

mechanical weathering that produces smaller, angular fragments of the same rock

Question 4

biological weathering

Answer 4

plants and animals chemically alter and physically break rocks through their growth and movement - not a separate type of weathering but a form of disintegration and decomposition

Question 5

erosion

Answer 5

wearing away of soil and rock particles that are moved elsewhere by a transport agent

Question 6

3 types of weathering

Answer 6

mechanical
chemical
biological

Question 7

oxidation

Answer 7

rocks exposed to air, ferrous soil oxidises and changes to ferric state
rocks exposed by digging, attrition, plate movement, bio. weathering

Question 8

oxidation equ.

Answer 8

4Fe + O2 –> 2Fe2O3

Question 9

carbonation-solution

Answer 9

calcium carbonate reacts with acid water, forming calcium bicarbonate which is soluble and is removed by percolating water

Question 10

carbonation-solution equ.

Answer 10

CO2 + H2O → H2CO3

Question 11

carbonation-solution conditions

Answer 11

rocks containing calcium carbonate - eg. limestone, generally warmer wetter climates, rainfall combines with CO2 to form a weak carbonic acid-higher pH = more effective

Question 12

hydrolysis

Answer 12

chemical breakdown of a substance when combined with water

Question 13

hydration

Answer 13

certain minerals in the rock absorb water, expand and change, causing mechanical stresses also

Question 14

hydration conditions

Answer 14

water absorbed into rocks - porous/cracked rocks make it more effective

Question 15

freeze-thaw

Answer 15

water seeps into crack in the rock, freezes, expands, pushing crack open wider, thaws and water fills the crack further, repeating the process, over time breaking the rock

Question 16

freeze-thaw conditions

Answer 16

coastal environments/environments where moisture is plentiful and temperature frequently fluctuates above and below freezing – eg. periglacial and alpine regions

Question 17

how do mudflows occur

[3]

Answer 17

A mud flow is caused by high water content of the regolith, so that internal cohesion is
reduced, and gravity causes movement downslope