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PHYSICAL GEOGRAPHY Weathering, Mass Wasting & Erosion C.J. Cox.

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Presentation on theme: "PHYSICAL GEOGRAPHY Weathering, Mass Wasting & Erosion C.J. Cox."— Presentation transcript:

1 PHYSICAL GEOGRAPHY Weathering, 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 –Frost Wedging –Joint Block Separation

9 Mechanical Weathering Breakdown 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 Weathering Rocks 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 Weathering Rocks 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

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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

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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 GEOGRAPHY Lithosphere Weathering, Mass Wasting & Erosion Chapter 13 C.J. Cox


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