PHYSICAL GEOGRAPHY Weathering, Mass Wasting

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PHYSICAL GEOGRAPHYWeathering, Mass Wasting
Erosion

• C.J. Cox

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• Weathering -
• the tearing down process reshaping the lithosphere

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• UPLIFTING

• TEARING DOWN
• gradational processes

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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

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Weathering Breakdown of materials

• Regolith - (greek)
• rhegos (blanket)
• lithos (rock)
• Loose material above the bedrock caused by
  weathing

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Weathering

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

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Exfoiliation Disintegration-
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• Joint Block Separation

• Frost Wedging

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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

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• Thermal Weathering

• Salt Wedging

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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

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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 -gt clay
• Oxidation - rusting (requires water)

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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

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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

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• Slumping - Earth flow

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• Soil Creep into terrasettes

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Mass Wasting Movement of materials downslope in
response to the Angle of Repose

• Solifluction - slow downslope movement of
  materials found in higher latitudes

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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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Agents of Erosion

• Water (most significant)
• Ice (Glaciers)
• Wind (arid regions where there is little
  vegetation)

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• Water Erosion

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• Ice Erosion

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• Wind Erosion

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Weathering, Mass Wasting Erosion

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

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PHYSICAL GEOGRAPHYLithosphereWeathering, Mass
Wasting Erosion

• Chapter 13
• C.J. Cox