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CH. 4 - WEATHERING     Chapter 2
Types of WeatheringProcesses1) Mechanical Weathering- rx break down into smaller    pieces- little or no chemical alteration
Types of WeatheringProcesses2) Chemical Weathering- alters crystalline structure and/or  composition of minerals- new mine...
Types of MechanicalWeathering1) Frost wedging- most effective in climates with   freeze/thaw cyclesEx: high altitudes, mid...
Granite boulder
Talus slope
Types of MechanicalWeathering2) Unloading- caused by a decrease in  pressure- effective on large bodies of  intrusive igne...
UnloadingRocks expand & crack parallel to  surface (“sheeting”)- produce rounded mountains  called exfoliation domesEx: Yo...
Unloading
YosemiteHalf Dome isan exfoliationdome cut inhalf by largeglaciersduring the IceAge
Types of MechanicalWeathering3) Abrasion- grinding by friction- usually done by water: rivers,  waves, glaciers- process b...
Types of MechanicalWeathering4) Organic ActivityEx: root wedging
Mechanical WeatheringWhere would it be most   significant?a) Amazon Rain Forestb) Peoria, ILc) North Pole
Chemical WeatheringNew minerals formed or old ones  dissolveAgents:1)Oxygen - abundant and reactive  Atomic Number = 8
OxygenEx: Mafic mineral + oxygen = iron                            oxideHornblende + Oxygen = Hematite
Agents of Chemical Weathering2) Acid – destroys crystalline   structureEx: How granite weathers (p. 89)Feldspar + acid = c...
Clay MineralsFamily of mineralsMicroscopic sheet silicates (like mini-micas)Ex: kaolinite
Sources of Acid:a) Volcanic eruptions
Volcanic acidsHot springs where water circulates near magma chambersEx: YellowstoneNational Park
Sources of Acidb) Mine Drainage- sulfur-bearing minerals react with  water to form sulfuric acidEx: Pyrite = FeS2 (iron su...
Open Pit Mine
Sources of Acidc) Air pollutionCoal-burning power plants release  sulfur into atmosphere- produce sulfuric acid (acid rain)
1990 Clean Air Act AmendmentsRequires power plants to reduce   pollutants1) Install “scrubbers” in   smokestacks2) Burn lo...
Map of U.S. coal deposits
Chemical WeatheringEnvironmental conditions that enhance chemical weathering:1)2)
Chemical WeatheringWhere would it be most  significant?a) Amazon Rain Forestb) Peoria, ILc) North Pole
Working together:Mechanical weathering creates smaller pieces w/ larger surface areas
Weathering ProductsOriginal Mineral      ProductHornblende          Clay mineralsFeldspar            Clay mineralsBiotite/...
Stable minerals at surface1) _______________________2) _______________________
Factors controlling rate ofweathering1) Particle size_________ particles = faster   chemical weathering_________ particles...
Factors controlling rate ofweathering2) CompositionWhich weathers faster in warm humid climate: basalt or granite?Basalt =...
Factors controlling rate ofweathering3) ClimateEx: Limestone in humid climate- chemical weathering dominates- rolling hill...
ClimateEx: Limestone in arid climate- mechanical weathering  dominates- steep cliffs with talus slopes
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04_weathering_students_revised

  1. 1. CH. 4 - WEATHERING Chapter 2
  2. 2. Types of WeatheringProcesses1) Mechanical Weathering- rx break down into smaller pieces- little or no chemical alteration
  3. 3. Types of WeatheringProcesses2) Chemical Weathering- alters crystalline structure and/or composition of minerals- new minerals formed or minerals dissolve
  4. 4. Types of MechanicalWeathering1) Frost wedging- most effective in climates with freeze/thaw cyclesEx: high altitudes, mid-latitudes
  5. 5. Granite boulder
  6. 6. Talus slope
  7. 7. Types of MechanicalWeathering2) Unloading- caused by a decrease in pressure- effective on large bodies of intrusive igneous rocks
  8. 8. UnloadingRocks expand & crack parallel to surface (“sheeting”)- produce rounded mountains called exfoliation domesEx: Yosemite National Park, CA Stone Mountain, GA
  9. 9. Unloading
  10. 10. YosemiteHalf Dome isan exfoliationdome cut inhalf by largeglaciersduring the IceAge
  11. 11. Types of MechanicalWeathering3) Abrasion- grinding by friction- usually done by water: rivers, waves, glaciers- process by which rivers & glaciers carve their own valleys
  12. 12. Types of MechanicalWeathering4) Organic ActivityEx: root wedging
  13. 13. Mechanical WeatheringWhere would it be most significant?a) Amazon Rain Forestb) Peoria, ILc) North Pole
  14. 14. Chemical WeatheringNew minerals formed or old ones dissolveAgents:1)Oxygen - abundant and reactive Atomic Number = 8
  15. 15. OxygenEx: Mafic mineral + oxygen = iron oxideHornblende + Oxygen = Hematite
  16. 16. Agents of Chemical Weathering2) Acid – destroys crystalline structureEx: How granite weathers (p. 89)Feldspar + acid = clay mineralClay minerals = most common weathering product of silicates
  17. 17. Clay MineralsFamily of mineralsMicroscopic sheet silicates (like mini-micas)Ex: kaolinite
  18. 18. Sources of Acid:a) Volcanic eruptions
  19. 19. Volcanic acidsHot springs where water circulates near magma chambersEx: YellowstoneNational Park
  20. 20. Sources of Acidb) Mine Drainage- sulfur-bearing minerals react with water to form sulfuric acidEx: Pyrite = FeS2 (iron sulfide) Galena = PbS (lead sulfide)
  21. 21. Open Pit Mine
  22. 22. Sources of Acidc) Air pollutionCoal-burning power plants release sulfur into atmosphere- produce sulfuric acid (acid rain)
  23. 23. 1990 Clean Air Act AmendmentsRequires power plants to reduce pollutants1) Install “scrubbers” in smokestacks2) Burn lower sulfur-content coal
  24. 24. Map of U.S. coal deposits
  25. 25. Chemical WeatheringEnvironmental conditions that enhance chemical weathering:1)2)
  26. 26. Chemical WeatheringWhere would it be most significant?a) Amazon Rain Forestb) Peoria, ILc) North Pole
  27. 27. Working together:Mechanical weathering creates smaller pieces w/ larger surface areas
  28. 28. Weathering ProductsOriginal Mineral ProductHornblende Clay mineralsFeldspar Clay mineralsBiotite/muscovite Clay mineralsQuartz Quartz
  29. 29. Stable minerals at surface1) _______________________2) _______________________
  30. 30. Factors controlling rate ofweathering1) Particle size_________ particles = faster chemical weathering_________ particles = faster mechanical weathering
  31. 31. Factors controlling rate ofweathering2) CompositionWhich weathers faster in warm humid climate: basalt or granite?Basalt = _____; Granite = _____
  32. 32. Factors controlling rate ofweathering3) ClimateEx: Limestone in humid climate- chemical weathering dominates- rolling hills- lots of caves & sinkholes
  33. 33. ClimateEx: Limestone in arid climate- mechanical weathering dominates- steep cliffs with talus slopes

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