2. Weathering: Disintegration of rocks in situ Physical Weathering  Size and shape of rocks altered but not the chemical composition  Angular and coarse end- products  Some involvement of water in the processes (e.g. freeze- thaw and salt crystal growth)  Effective in extreme climate conditions Chemical Weathering  Physical structure and chemical composition of rocks altered  Finer end-products (e.g. clay and sand)  Water (rainwater, seawater) is important as the main solvent in all processes  Effective in vegetated areas and hot and wet climate

3. Chemical WeatheringChemical Weathering  Hydrolysis  Carbonation  Oxidation  Solution

4. Karst LandscapeKarst Landscape

5. Insolation WeatheringInsolation Weathering

6. Pressure ReleasePressure Release

7. Salt Crystal GrowthSalt Crystal Growth

8. Freeze-Thaw Action/ Frost Shattering

11. Factor 1: Rock HardnessFactor 1: Rock Hardness  Rock Hardness- dependent on minerals that form rocks and how minerals are cemented together  Igneous stronger than Sedimentary rocks. Why?  Least important factor since all rocks ultimately experience weathering once they are exposed to weathering agents

12. Factor 2: Mineral composition  Influence rock resistance to chemical weathering  Weaker minerals: calcium carbonate, olivine and pyroxene  Stronger minerals: quartz  Influence also physical weathering like insolation weathering because of differences in coefficient of expansion and contraction of minerals

13. Factor 3: Grain size of rocks  Coarse-grained rocks weathered down faster than fine- grained rocks  When minerals susceptible to changes are altered (e.g. feldspar), larger gaps are formed, weakened structure, larger gap provides bigger surface area for further chemical attack

14. Factor 4: Lines of Weakness of rocks  Lines of weakness (e.g. cracks, joints, bedding planes) found in rocks make them more susceptible to both physical and chemical weathering. How?  The more well-jointed the rock is, the faster the rate of physical, chemical and even biological weathering

16. Factor 5: ReliefFactor 5: Relief  On flat land, soil and weathered materials can retain water which seeps through them and acts on the underlying rocks chemically  On slopes, mass movements, like landslides and slumping, expose more underlying rocks for physical weathering.  Chemical weathering less effective on steep slopes as water flows away

17. Factor 6: Vegetation coverFactor 6: Vegetation cover  Vegetation cover can retain rainwater and keeps underlying rocks moist for chemical weathering to take place  Biological weathering common too

18. Factor 7: Human activitiesFactor 7: Human activities  How do human activities contribute to weathering?

19. Weathering regions of the world in relation to mean annual temperature and precipitation (Peltier,1950)