1. A) Mechanical / Physical weathering:
Never in isolation
Granular disintegration

2. Frost shattering:

3. Insolation weathering:

4. Wetting and drying (slaking):

5. Exfoliation (spheroidal weathering):

6. Salt crystal growth:

7. pressure release - dilation

8. Organic action:

9. B) Chemical Weathering:
decomposition of minerals so the chemistry of the rock is altered.
H2O + CO2 <=> H2CO3
Best in warm, humid conditions

10. Hydrolysis:
H+ ions in water react to give clays.
Rocks containing feldspar are particularly vulnerable (eg granite)

11. Hydration:
the absorption of water into the crystal structure can weaken the rock
Also a physical process (brown flakes)

12. Carbonation:
H2CO3 + CaCO3 <=> Ca (HCO3)2
Calcium hydrogen carbonate (or calcium bicarbonate) is very soluble in water and so the limestone dissolves

14. Solution:
Some rocks simply dissolve eg halite (rock salt)

15. Oxidation: Minerals react with oxygen to form oxides or hydroxides
eg ‘rusting’, where iron in ferrous form is oxidised into its ferric form

16. Humic (organic) acid from decaying flora & fauna attack certain minerals
Lichens extract iron
Chelation:

17. Rates of weathering depend on:
Rock type: quartz is unaffected by solution, hydrolysis and oxidation
(sand on a beach)

18. Rock structure (joints):

19. Climate:
A temperature ‘range’
Water
Vegetation