Chapter 15: Weathering and Mass Wasting Physical Geography Ninth Edition Robert E. Gabler James. F. Petersen L. Michael Tr...
Weathering and Mass Wasting
Weathering and Mass Wasting <ul><li>Exogenic processes: </li></ul><ul><ul><li>Breakdown rocks  </li></ul></ul><ul><ul><li>...
15.1 Nature of Exogenic Processes <ul><li>Weathering: breakdown of rock materials at and near Earth’s surface </li></ul><u...
15.1 Nature of Exogenic Processes <ul><li>Q: Can you identify evidence of the three phases shown in Figure 15.3?  </li></ul>
15.2 Weathering <ul><li>3 Types of Weathering </li></ul><ul><ul><li>Physical weathering </li></ul></ul><ul><ul><li>Mechani...
15.2 Weathering <ul><li>Physical Weathering </li></ul><ul><ul><li>Person breaking a rock </li></ul></ul><ul><ul><li>Unload...
15.2 Weathering <ul><li>Unloading </li></ul><ul><ul><li>Erosional stripping of overlying rocks and ultimate removal of ove...
15.2 Weathering <ul><li>Unloading </li></ul><ul><ul><li>Exfoliation </li></ul></ul><ul><ul><li>Exfoliation sheet  </li></u...
15.2 Weathering <ul><li>Thermal Expansion and Contraction </li></ul><ul><ul><li>Granular disintegration </li></ul></ul><ul...
15.2 Weathering <ul><li>Freeze-Thaw Weathering </li></ul><ul><ul><li>Also called frost weathering (ice wedging) </li></ul>...
15.2 Weathering <ul><li>Salt Crystal Growth </li></ul><ul><ul><li>Water with dissolved salt accumulates in these spaces an...
15.2 Weathering <ul><li>Chemical Weathering </li></ul><ul><ul><li>Most important catalysts and reactive agents: </li></ul>...
15.2 Weathering <ul><li>Oxidation </li></ul><ul><ul><li>Iron and aluminum oxides </li></ul></ul><ul><ul><li>Very common </...
15.3 Variability in Weathering <ul><li>Effectiveness of Weathering </li></ul><ul><ul><li>Climate </li></ul></ul><ul><ul><l...
15.3 Variability in Weathering <ul><li>Climate </li></ul><ul><ul><li>Q: In which weathering region would we find a site th...
15.3 Variability in Weathering <ul><li>Climate </li></ul>
15.3 Variability in Weathering <ul><li>Rock Type </li></ul><ul><ul><li>Differential weathering and erosion </li></ul></ul>...
15.3 Variability in Weathering <ul><li>Structural Weakness </li></ul><ul><ul><li>Spheroidal weathering </li></ul></ul><ul>...
15.3 Variability in Weathering <ul><li>Topography Related to Differential Weathering and Erosion </li></ul><ul><li>Grand C...
15.3 Variability in Weathering <ul><li>Topography Related to Differential Weathering and Erosion </li></ul><ul><ul><li>Q: ...
15.4 Mass Wasting <ul><li>Mass Movement </li></ul><ul><ul><li>Downslope transport of material due to gravity </li></ul></u...
15.4 Mass Wasting <ul><li>Mass Movement </li></ul><ul><ul><li>Slope angle </li></ul></ul><ul><ul><li>Creeping, falling, sl...
15.4 Mass Wasting <ul><li>Classification of Mass Wasting </li></ul><ul><ul><li>Types of Earth Material </li></ul></ul><ul>...
15.4 Mass Wasting <ul><li>Slow mass wasting </li></ul><ul><ul><li>Creep </li></ul></ul><ul><ul><ul><li>Slow migration, but...
15.4 Mass Wasting <ul><li>Q: What other constructed features might be changed by creep? </li></ul>
15.4 Mass Wasting <ul><li>Slow mass wasting </li></ul><ul><ul><li>Solifluction </li></ul></ul><ul><ul><ul><li>Most common ...
15.4 Mass Wasting <ul><li>Fast Mass Wasting </li></ul><ul><ul><li>Four Major Types: </li></ul></ul><ul><ul><ul><li>Falls <...
15.4 Mass Wasting <ul><li>Falls </li></ul><ul><ul><li>Rockfalls </li></ul></ul><ul><ul><li>Due to: </li></ul></ul><ul><ul>...
15.4 Mass Wasting <ul><li>Falls </li></ul><ul><ul><li>Talus slope </li></ul></ul><ul><ul><li>Talus cone </li></ul></ul><ul...
15.4 Mass Wasting <ul><li>Falls </li></ul><ul><ul><li>Happy Isles Rockfall in Yosemite Valley, CA </li></ul></ul><ul><ul><...
15.4 Mass Wasting <ul><li>Avalanches </li></ul><ul><ul><li>Snow  </li></ul></ul><ul><ul><li>Rock </li></ul></ul><ul><ul><l...
15.4 Mass Wasting <ul><li>Slides </li></ul><ul><ul><li>Water plays biggest role </li></ul></ul><ul><ul><li>Rockslides </li...
15.4 Mass Wasting <ul><li>Slides </li></ul><ul><ul><li>Debris slide </li></ul></ul><ul><ul><li>Mudslide </li></ul></ul><ul...
15.4 Mass Wasting <ul><li>Flows </li></ul><ul><ul><li>Earthflow </li></ul></ul><ul><ul><li>Slump-earthflow </li></ul></ul>...
15.5 Weathering, Mass Wasting, and the Landscape <ul><ul><li>Violent 1980 eruption of Mount St. Helens in Washington creat...
Physical Geography End of Chapter 15: Weathering and Mass Wasting
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  • Insert cover image for Chapter 15 (p. 410).
  • Insert Figure 15.1 and 15.2
  • Insert Figure 15.3 and 15.4
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  • Insert Figure 15.8 and 15.9
  • Insert Figure 15.10 and 15.11
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  • Insert Figure 15.13 and 15.14
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  • Insert Figure 15.17 and 15.18
  • Insert Figure 15.19b and 15.20
  • Insert Figure 15.21 and 15.22
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  • Insert Table 15.1
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  • Insert Figure 15.31 and 15.32
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  • 15

    1. 1. Chapter 15: Weathering and Mass Wasting Physical Geography Ninth Edition Robert E. Gabler James. F. Petersen L. Michael Trapasso Dorothy Sack
    2. 2. Weathering and Mass Wasting
    3. 3. Weathering and Mass Wasting <ul><li>Exogenic processes: </li></ul><ul><ul><li>Breakdown rocks </li></ul></ul><ul><ul><li>Erode rock materials </li></ul></ul><ul><ul><li>Transport them </li></ul></ul><ul><li>Relocation by </li></ul><ul><ul><li>Gravity </li></ul></ul><ul><ul><li>Geomorphic Agents </li></ul></ul><ul><ul><ul><li>Flowing water, wind </li></ul></ul></ul><ul><ul><ul><li>Moving ice, waves </li></ul></ul></ul>
    4. 4. 15.1 Nature of Exogenic Processes <ul><li>Weathering: breakdown of rock materials at and near Earth’s surface </li></ul><ul><li>Mass wasting </li></ul>
    5. 5. 15.1 Nature of Exogenic Processes <ul><li>Q: Can you identify evidence of the three phases shown in Figure 15.3? </li></ul>
    6. 6. 15.2 Weathering <ul><li>3 Types of Weathering </li></ul><ul><ul><li>Physical weathering </li></ul></ul><ul><ul><li>Mechanical weathering </li></ul></ul><ul><ul><li>Chemical weathering </li></ul></ul><ul><ul><li>Q: How might an animal cause physical weathering? </li></ul></ul>
    7. 7. 15.2 Weathering <ul><li>Physical Weathering </li></ul><ul><ul><li>Person breaking a rock </li></ul></ul><ul><ul><li>Unloading </li></ul></ul><ul><ul><li>Thermal Expansion and Contraction </li></ul></ul><ul><ul><li>Freeze-Thaw </li></ul></ul><ul><ul><li>Salt Crystal growth </li></ul></ul><ul><ul><li>Hydration </li></ul></ul>
    8. 8. 15.2 Weathering <ul><li>Unloading </li></ul><ul><ul><li>Erosional stripping of overlying rocks and ultimate removal of overlying weight </li></ul></ul><ul><ul><li>High elevation increases process </li></ul></ul>
    9. 9. 15.2 Weathering <ul><li>Unloading </li></ul><ul><ul><li>Exfoliation </li></ul></ul><ul><ul><li>Exfoliation sheet </li></ul></ul><ul><ul><li>Exfoliation dome </li></ul></ul><ul><ul><ul><li>Stone Mountain, Georgia </li></ul></ul></ul><ul><ul><ul><li>Half Dome (Yosemite) </li></ul></ul></ul>
    10. 10. 15.2 Weathering <ul><li>Thermal Expansion and Contraction </li></ul><ul><ul><li>Granular disintegration </li></ul></ul><ul><ul><ul><li>Differential thermal expansion and contraction of individual mineral grains in coarse crystalline rocks </li></ul></ul></ul>
    11. 11. 15.2 Weathering <ul><li>Freeze-Thaw Weathering </li></ul><ul><ul><li>Also called frost weathering (ice wedging) </li></ul></ul><ul><ul><li>Water freezes it expands 9% </li></ul></ul><ul><ul><li>Pipes bursting </li></ul></ul><ul><ul><li>Angular blocks </li></ul></ul><ul><ul><li>Effective in the upper-middle and lower-high latitudes </li></ul></ul>
    12. 12. 15.2 Weathering <ul><li>Salt Crystal Growth </li></ul><ul><ul><li>Water with dissolved salt accumulates in these spaces and then evaporates, and growing salt crystals wedge rocks apart </li></ul></ul><ul><li>Hydration </li></ul>
    13. 13. 15.2 Weathering <ul><li>Chemical Weathering </li></ul><ul><ul><li>Most important catalysts and reactive agents: </li></ul></ul><ul><ul><ul><li>Water </li></ul></ul></ul><ul><ul><ul><li>Oxygen </li></ul></ul></ul><ul><ul><ul><li>Carbon dioxide </li></ul></ul></ul><ul><ul><li>3 Types of chemical weathering: </li></ul></ul><ul><ul><ul><li>Oxidation </li></ul></ul></ul><ul><ul><ul><li>Carbonation and Solution </li></ul></ul></ul><ul><ul><ul><li>Hydrolysis </li></ul></ul></ul>
    14. 14. 15.2 Weathering <ul><li>Oxidation </li></ul><ul><ul><li>Iron and aluminum oxides </li></ul></ul><ul><ul><li>Very common </li></ul></ul><ul><li>Carbonation and Solution </li></ul><ul><ul><li>Occurs when carbon dioxide in water reacts with rock material to produce bicarbonate ions </li></ul></ul>
    15. 15. 15.3 Variability in Weathering <ul><li>Effectiveness of Weathering </li></ul><ul><ul><li>Climate </li></ul></ul><ul><ul><li>Type of rock </li></ul></ul><ul><ul><li>Nature and amount of fractures </li></ul></ul>
    16. 16. 15.3 Variability in Weathering <ul><li>Climate </li></ul><ul><ul><li>Q: In which weathering region would we find a site that has an annual mean temperature of 5 o C (41 o F) and an annual rainfall of 100 cm (40 in)? </li></ul></ul>
    17. 17. 15.3 Variability in Weathering <ul><li>Climate </li></ul>
    18. 18. 15.3 Variability in Weathering <ul><li>Rock Type </li></ul><ul><ul><li>Differential weathering and erosion </li></ul></ul><ul><ul><li>Strong rock may be easily eroded in a different environment </li></ul></ul><ul><li>Structural Weakness </li></ul><ul><ul><li>Joints and fractures </li></ul></ul><ul><ul><li>Exposed rock, collect salts, accumulation of water, and plants </li></ul></ul>
    19. 19. 15.3 Variability in Weathering <ul><li>Structural Weakness </li></ul><ul><ul><li>Spheroidal weathering </li></ul></ul><ul><ul><li>Q: With north at the top of this photo, what directions do the two most apparent joint sets trend? </li></ul></ul>
    20. 20. 15.3 Variability in Weathering <ul><li>Topography Related to Differential Weathering and Erosion </li></ul><ul><li>Grand Canyon </li></ul>
    21. 21. 15.3 Variability in Weathering <ul><li>Topography Related to Differential Weathering and Erosion </li></ul><ul><ul><li>Q: Can you see how the topography of the Ridge and Valley section influences human settlement patterns? </li></ul></ul>
    22. 22. 15.4 Mass Wasting <ul><li>Mass Movement </li></ul><ul><ul><li>Downslope transport of material due to gravity </li></ul></ul><ul><ul><li>Q: What other kinds of problems on roads are related to mass wasting? </li></ul></ul>
    23. 23. 15.4 Mass Wasting <ul><li>Mass Movement </li></ul><ul><ul><li>Slope angle </li></ul></ul><ul><ul><li>Creeping, falling, sliding, or flowing </li></ul></ul><ul><ul><li>Gravity is the principal force </li></ul></ul><ul><ul><li>Water is also a contributing factor </li></ul></ul>
    24. 24. 15.4 Mass Wasting <ul><li>Classification of Mass Wasting </li></ul><ul><ul><li>Types of Earth Material </li></ul></ul><ul><ul><ul><li>Soil </li></ul></ul></ul><ul><ul><ul><li>Debris </li></ul></ul></ul><ul><ul><ul><li>Mud </li></ul></ul></ul><ul><ul><li>Categorized by speed </li></ul></ul><ul><ul><ul><li>Slow mass wasting </li></ul></ul></ul><ul><ul><ul><li>Fast mass wasting </li></ul></ul></ul>
    25. 25. 15.4 Mass Wasting <ul><li>Slow mass wasting </li></ul><ul><ul><li>Creep </li></ul></ul><ul><ul><ul><li>Slow migration, but most persistent </li></ul></ul></ul><ul><ul><ul><li>Heaving process </li></ul></ul></ul><ul><ul><li>Q: Are there places near where you live that show evidence of soil creep? </li></ul></ul>
    26. 26. 15.4 Mass Wasting <ul><li>Q: What other constructed features might be changed by creep? </li></ul>
    27. 27. 15.4 Mass Wasting <ul><li>Slow mass wasting </li></ul><ul><ul><li>Solifluction </li></ul></ul><ul><ul><ul><li>Most common in high latitudes of high-elevation tundra </li></ul></ul></ul><ul><ul><ul><li>Permafrost and active layer </li></ul></ul></ul><ul><ul><ul><li>Summer thaw </li></ul></ul></ul><ul><ul><ul><li>Tundra landscapes </li></ul></ul></ul><ul><ul><li>Q: How does solifluction differ from soil creep? </li></ul></ul>
    28. 28. 15.4 Mass Wasting <ul><li>Fast Mass Wasting </li></ul><ul><ul><li>Four Major Types: </li></ul></ul><ul><ul><ul><li>Falls </li></ul></ul></ul><ul><ul><ul><li>Avalanches </li></ul></ul></ul><ul><ul><ul><li>Slides </li></ul></ul></ul><ul><ul><ul><li>Flows </li></ul></ul></ul><ul><ul><li>Effects more dramatic than slow mass wasting </li></ul></ul>
    29. 29. 15.4 Mass Wasting <ul><li>Falls </li></ul><ul><ul><li>Rockfalls </li></ul></ul><ul><ul><li>Due to: </li></ul></ul><ul><ul><ul><li>Weathering weakens the bonds between clasts and cliff </li></ul></ul></ul><ul><ul><ul><li>Large rock masses that fall from a cliff face or an overhanging ledge </li></ul></ul></ul>
    30. 30. 15.4 Mass Wasting <ul><li>Falls </li></ul><ul><ul><li>Talus slope </li></ul></ul><ul><ul><li>Talus cone </li></ul></ul><ul><ul><li>Angle of repose </li></ul></ul>
    31. 31. 15.4 Mass Wasting <ul><li>Falls </li></ul><ul><ul><li>Happy Isles Rockfall in Yosemite Valley, CA </li></ul></ul><ul><ul><li>Traveled at an estimated 250 km/hr (160 mph) </li></ul></ul>
    32. 32. 15.4 Mass Wasting <ul><li>Avalanches </li></ul><ul><ul><li>Snow </li></ul></ul><ul><ul><li>Rock </li></ul></ul><ul><ul><li>Debris </li></ul></ul>
    33. 33. 15.4 Mass Wasting <ul><li>Slides </li></ul><ul><ul><li>Water plays biggest role </li></ul></ul><ul><ul><li>Rockslides </li></ul></ul><ul><ul><li>Threaten lives and property </li></ul></ul><ul><ul><li>Hebgen Lake rockslide </li></ul></ul><ul><ul><ul><li>Southwestern Montana (1959) </li></ul></ul></ul><ul><ul><ul><li>Killed 28 people </li></ul></ul></ul>
    34. 34. 15.4 Mass Wasting <ul><li>Slides </li></ul><ul><ul><li>Debris slide </li></ul></ul><ul><ul><li>Mudslide </li></ul></ul><ul><ul><li>Slumps </li></ul></ul><ul><ul><li>Landslide </li></ul></ul>
    35. 35. 15.4 Mass Wasting <ul><li>Flows </li></ul><ul><ul><li>Earthflow </li></ul></ul><ul><ul><li>Slump-earthflow </li></ul></ul><ul><ul><li>Debris flows </li></ul></ul><ul><ul><li>Mudflows </li></ul></ul><ul><ul><li>Flow levees </li></ul></ul>
    36. 36. 15.5 Weathering, Mass Wasting, and the Landscape <ul><ul><li>Violent 1980 eruption of Mount St. Helens in Washington created lahars - mudflows </li></ul></ul>
    37. 37. Physical Geography End of Chapter 15: Weathering and Mass Wasting
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