PHYSICAL GEOGRAPHY Weathering, Mass Wasting & Erosion

1. PHYSICAL GEOGRAPHYWeathering, Mass Wasting & Erosion C.J. Cox

2. Weathering - • the tearing down process reshaping the lithosphere

3. UPLIFTING TEARING DOWN gradational processes

4. Weathering, Mass Wasting & Erosion • Weathering - the tearing down process • breakdown of materials • Most landscapes are a combination of mechanical and chemical weathering • Mass Wasting - massive movement of materials downslope • Erosion - the removal of material

5. Weathering Breakdown of materials • Regolith - (greek) • rhegos (blanket) • lithos (rock) • Loose material above the bedrock caused by weathing

6. Weathering • Weathering occurs much faster along cracks or joints and faults • Exfoiliation • unloading of overlying pressure • slabs separating • Disintegration- rock falls, splits crumbles • granite -> sand (granular disintegration)

7. Exfoiliation Disintegration-

8. Joint Block Separation Frost Wedging

9. Mechanical WeatheringBreakdown of rocks without change to chemical composition • Frost Wedging - water expands as it freezes and breaks apart rocks • Salt Wedging - pitted surfaces • Thermal Weathering - extremes of temperatures on rocks • outer part is heated & expands during the day • at night outer rock contracts • inner part remains cool

10. Thermal Weathering Salt Wedging

11. Mechanical Weathering Breakdown of rocks with change to chemical composition • Organic - plant roots and small burrowing animals break up rocks • Unloading - abrasive action of water, wind and ice • less pressure on surface causes expansion & fracturing

12. Chemical WeatheringRocks break up because of chemical composition change • Decomposition - alterations in chemical composition • Carbonation - CO2 & H20 = carbonic acid • carbonic acid dissolves limestone & creates caverns • feldspar -> clay • Oxidation - rusting (requires water)

13. Chemical WeatheringRocks break up because of chemical composition change • Hydrolysis - moisture in rock cavities • H20 & salts =acids which cause the break down of rock • Solution - water dissolving rock particles • limestone

15. Mass Wasting Movement of materials downslope in response to the Angle of Repose • Soil Creep - slow movement found on gentle slopes • Slumping and Earth Flows - forms of earth collapse caused by water logged soils • Mud Flows - rapid movement of moisture saturated soil • often occur after violent storms

16. Slumping - Earth flow

17. Soil Creep into terrasettes

18. Mass Wasting Movement of materials downslope in response to the Angle of Repose • Solifluction - slow downslope movement of materials found in higher latitudes

19. Mass Wasting Movement of materials downslope in response to the Angle of Repose • Rock Falls - loosened fragments of rocks known as talus fall down slope • talus slopes • Landslides - massive movement of materials occuring on steep face slopes • Avalanche - down slope movement of snow, ice, or rock

23. Agents of Erosion • Water (most significant) • Ice (Glaciers) • Wind (arid regions where there is little vegetation)

24. Water Erosion

25. Ice Erosion

26. Wind Erosion

27. Weathering, Mass Wasting & Erosion • Weathering - the tearing down process • breakdown of materials • Mass Wasting - massive movement of materials downslope • Erosion - the removal of material

28. PHYSICAL GEOGRAPHYLithosphereWeathering, Mass Wasting & Erosion Chapter 13 C.J. Cox