1. Geology: Processes, Hazards, and Soils Brian Kaestner Saint Mary’s Hall Brian Kaestner Saint Mary’s Hall Thanks to Miller and Clements

6. Geologic Processes  Structure of the Earth Mantle Core Crust Low-velocity zone Solid Outer core (liquid) Inner core (solid) 35 km (21 mi.) avg., 1,200˚C 2,900km (1,800 mi.) 3,700˚C 5,200 km (3,100 mi.), 4,300˚C 10 to 65km 100 km 200 km 100 km (60 mi.) 200 km (120 mi.) Crust Lithosphere Asthenosphere (depth unknown) Fig. 10.2, p. 212

7. Composition of Earth’s Crust Earth’s Crust Oxygen 46.6% Silicon 27.7% All others 1.5% Magnesium 2.1% Potassium 2.6% Sodium 2.8% Calcium 3.6% Iron 5.0% Aluminum 8.1% Fig. 10.4, p. 213

8. Features of the Crust Oceanic crust (lithosphere)AbyssalhillsAbyssalfloorOceanicridgeTrench Volcanoes Folded mountain belt Craton Mantle (lithosphere) Mantle (asthenosphere) Abyssal plain Continental crust (lithosphere) Mantle(lithosphere) Continental rise Continental slope Continental shelf Abyssal plain Abyssalfloor Fig. 10.3, p. 213

9. Fig. 10.5b, p. 214 EURASIAN PLATE CHINA SUBPLATE PHILIPINE PLATE INDIAN-AUSTRLIAN PLATE PACIFIC PLATE JUAN DE FUCA PLATE COCOS PLATE CARIBBEAN PLATE NORTH AMERICAN PLATE SOUTH AMERICAN PLATE EURASIAN PLATE ANATOLIAN PLATE ARABIAN PLATE AFRICAN PLATE AFRICAN PLATE Carlsberg Ridge Southwest Indian Ocean Ridge ANTARCTIC PLATE Transform fault East Pacific Rise Transform fault Mid- Indian Ocean Ridge Southeast Indian Ocean Ridge Mid- Atlantic Ocean Ridge Reykjanes Ridge Transform fault Divergent ( ) and transform fault ( ) boundaries Convergent plate boundaries Plate motion at convergent plate boundaries Plate motion at divergent plate boundaries

10. Internal Earth Processes  Plate tectonics  Divergent boundary  Convergent boundary  Subduction zone  Transform fault  Ring of Fire Lithosphere Asthenosphere Oceanic ridge at a divergent plate boundary Lithosphere Trench Volcanic island arc Asthenosphere Rising magma Subduction zone Trench and volcanic island arc at a convergent plate boundary Fracture zone Transform fault Lithosphere Asthenosphere Transform fault connecting two divergent plate boundaries Fig. 10.6, p. 215 Refer to Fig. 10-5 p. 214

11. Fig. 10.6a, p. 215 Lithosphere Asthenosphere Oceanic ridge at a divergent plate boundary

12. Fig. 10.6b, p. 215 Lithosphere TrenchVolcanic island arc Asthenosphere Rising magma Subduction zone Trench and volcanic island arc at a convergent plate boundary

13. Fig. 10.6c, p. 215 Fracture zone Transform fault Lithosphere Asthenosphere Transform fault connecting two divergent plate boundaries

14. Fig. 10.7, p. 216 Dunes Lagoon Spits Stream Glacier Lake Tidal flat Barrier islands Shallow marine environment Volcanic island Coral reef Abyssal plain Deep-sea fan Continental shelf Continental slope Continental rise Delta Dunes Beach Shallow marine environment

15. External Earth Processes  Erosion  Mechanical weathering  Frost wedging  Chemical weathering Refer to Fig. 10-7 p. 216

16. Minerals and Rocks  Mineral (diamond, bauxite) Rock Types  Igneous (granite, lava)  Sedimentary (limestone, sandstone)  Metamorphic (marble, slate)

17. The Rock Cycle Igneous Rock Granite, Pumice, Basalt Sedimentary Rock Shale, Sandstone, Limestone Metamorphic Rock Slate, Quartzite, Marble Magma (Molten Rock) Weathering Erosion Transport Deposition External Processes Internal Processes External Processes Internal Processes Heat, Pressure Heat, Pressure Heat, Pressure Heat, Pressure Fig. 10.8, p. 217

18. Natural Hazards: Earthquakes  Features  Magnitude  Aftershocks  Primary effects  Secondary effects Liquefaction of recent sediments causes buildings of sink Landslides may occur on hilly ground Shockwaves Epicenter Focus Two adjoining plates move laterally along the fault line Earth movements Cause flooding in Low-lying areas Fig. 10.9, p. 217

19. Expected Earthquake Damage Canada United States No damage expected Minimal damage Moderate damage Severe damage Fig. 10.10, p. 218

20. Natural Hazards: Volcanic Eruptions extinct volcanoes magma reservoir central vent magma conduit Solidlithosphere Upwelling magma Partially molten asthenosphere Fig. 10.11, p. 218 See Spotlight p. 219

21. Fig. 10.5a, p. 214 VolcanoesEarthquakes

22. Soils: Formation  Soil horizons  Soil profile  Humus O horizon Leaf litter A horizon Topsoil B horizon Subsoil C horizon Parentmaterial Mature soil Young soil RegolithRegolith BedrockBedrock Immature soil Fig. 10.12, p. 220

23. Fig. 10.13, p. 221 Flatworm Rove beetle Ant Centipede Mite Pseudoscorpion Ground beetle Adult fly Millipede Fly larvae Sowbug Mite Earthworms Slug Snail Roundworms Protozoa Bacteria Organic debris Beetle Mites Fungi Springtail Actinomycetes

24. Soil Properties  Infiltration  Leaching  Porosity/permeability  Texture  Structure  pH 100%clayIncreasing percentage silt Increasing percentage clay 0 20 40 60 80 80 60 40 20 0 100%sand 80604020 100%silt Increasing percentage sand Fig. 10.16, p. 224 Water High permeabilityLow permeability Fig. 10.17, p. 224

25. Water High permeabilityLow permeability

26. Fig. 10.16, p. 224 100%clay Increasing percentage silt Increasing percentage clay 0 20 40 60 80 60 40 20 0 100%sand80604020100%silt Increasing percentage sand sandy clay silty clay silty clay loam clay loam silty loam silt sandy clay loam sandy loam loamy sand

27. Table 10-1 p. 225 TextureNutrientInfiltrationWater-HoldingAerationTilthCapacity ClayGoodPoorGoodPoorPoor SiltMediumMediumMediumMediumMedium SandPoorGoodPoorGoodGood Loam MediumMediumMediumMediumMedium Fig. 10.15b, p. 223

28. Fig. 10.15a, p. 223 Weak humus- mineral mixture Mosaic of closely packed pebbles, boulders Dry, brown to reddish-brown with variable accumulations of clay, calcium carbonate, and soluble salts Desert Soil (hot, dry climate) Grassland Soil (semiarid climate) Alkaline, dark, and rich in humus Clay, calcium compounds

29. Fig. 10.15b, p. 223 Acidic light- colored humus Iron and aluminum compounds mixed with clay Forest litter leaf mold Humus-mineral mixture Light, grayish- brown, silt loam Dark brown Firm clay Acid litter and humus Humus and iron and aluminum compounds Light-colored and acidic Tropical Rain Forest Soil (humid, tropical climate) Deciduous Forest Soil (humid, mild climate) Coniferous Forest Soil (humid, cold climate)

30. Areas of serious concern Areas of some concern Stable or nonvegetative areas Global Soil Erosion Fig. 10.19, p. 226

31. Fig. 10.20, p. 227 Colorado Kansas Dust Bowl Oklahoma New Mexico Texas MEXICO

32. Soils: Degradation  Desertification  Salinization  Waterlogging Evaporation Transpiration Evaporation Waterlogging Less permeable clay layer Fig. 10.22, p. 229

33. Fig. 10.21, p. 228 ModerateSevereVery Severe desertification

34. Fig. 10.23, p. 229

35. Solutions: Soil Conservation  Conventional-tillage  Conservation tillage  Cropping methods  Windbreaks  Land Classification Refer to Fig. 10-24 p. 230

36. Fig. 10.24d, p. 230 Windbreaks

37. Fig. 10.24c, p. 230 Alley cropping

38. Fig. 10.24b, p. 230 Control planting and strip cropping

39. Soil Restoration  Organic fertilizer  Animal manure  Green manure  Compost  Crop rotation  Commercial inorganic fertilizer