1. Geology: Processes, Hazards, and Soils Chapter 10 G. Tyler Miller’s Living in the Environment 13 th Edition Chapter 10 G. Tyler Miller’s Living in the Environment 13 th Edition

2. Key Concepts Internal geologic processes Internal geologic processes External geologic processes External geologic processes Minerals, rocks, and the rock cycle Minerals, rocks, and the rock cycle Earthquakes and volcanoes Earthquakes and volcanoes Soil structure and formation Soil structure and formation Soil conservation Soil conservation

3. Geologic Processes Earth’s internal structure Fig. 10-2 p. 204

4. Eight Most Common Chemical Elements (%) WHOLE EARTH CRUST Iron33.3Oxygen45.2 Oxygen29.8Silicon27.2 Silicon15.6Aluminum8.2 Magnesium13.9Iron5.8 Nickel2.0Calcium5.1 Calcium1.8Magnesium2.8 Aluminum1.5Sodium2.3 Sodium0.2Potassium1.7

5. Features of the Crust

6. Oceanic crust (lithosphere) Abyssal hills Abyssal floor Oceanic ridge Trench Volcanoes Folded mountain belt Craton Mantle (lithosphere) Mantle (asthenosphere) Abyssal plain Continental crust (lithosphere) Mantle (lithosphere) Continental rise Continental slope Continental shelf Abyssal plain Abyssal floor

7. Internal Earth Processes Geological changes originating from the earth’s interiorGeological changes originating from the earth’s interior –Residual heat from the earth’s core –Radioactive decay in the earth’s crust Convection cellsConvection cells Mantle plumesMantle plumes

8. Tectonic plate Collision between two continents Oceanic tectonic plate Spreading center Oceanic tectonic plate Ocean trench Plate movement Continental crust Subduction zone Oceanic crust Oceanic crust Continental crust Mantle Inner core Hot outer core Two plates move towards each other. One is subducted back into the mantle on falling convection current. Mantle convection cell Hot material rising through the mantle Material cools as it reaches the outer mantle Cold dense material falls back through mantle

9. EURASIAN PLATE CHINASUBPLATE PHILIPPINEPLATE INDIAN-AUSTRLIAN PLATE PACIFIC PLATE JUAN DE FUCA PLATE COCOS PLATE CARIBBEAN PLATE PLATE NORTHAMERICAN SOUTHAMERICAN EURASIAN ANATOLIAN ARABIAN AFRICAN SOMALIAN SUBPLATE 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. Plate Tectonics Theory explaining the movement of tectonic plates and the processes that occur at their boundaries. –more commonly referred to as “continental drift”

11. Tectonic Plate Boundaries  Divergent boundary  Convergent boundary Subduction zone  Convergent boundary Subduction zone  Transform fault

12. Lithosphere Asthenosphere Oceanic ridge at a divergent plate boundary Divergent Boundary

13. Lithosphere TrenchVolcanic island arc Asthenosphere Risingmagma Subductionzone Trench and volcanic island arc at a convergent plate boundary Convergent Boundary

14. Fracture zone Transform fault Lithosphere Asthenosphere Transform fault connecting two divergent plate boundaries Transform Faults

15. VolcanoesEarthquakes Ring of Fire

16. Natural Hazards: Earthquakes FeaturesFeatures –Shock waves –Focus and epicenter MagnitudeMagnitude –Richter Scale –1(insignificant) to 9 (great) 10X AftershocksAftershocks Primary EffectsPrimary Effects –shaking Secondary EffectsSecondary Effects –Rockslides, fires, and flooding –tsunamis

17. Expected Earthquake Damage Fig. 10-10 p. 211 Canada United States No damage expected Minimal damage Moderate damage Severe damage

18. Natural Hazards: Volcanic Eruptions Ejecta (rock and ash) Molten lava Gases extinct volcanoes extinct volcanoes magma reservoir central vent magma conduit Solid lithosphere Solid lithosphere Upwelling magma Partially molten asthenosphere

19. External Earth Processes Weathering – breakdown of solid rockWeathering – breakdown of solid rock –Mechanical (physical) weathering Frost wedgingFrost wedging –Chemical weathering OxidationOxidation HydrolysisHydrolysis Erosion – process by which earth particles are moved from one place and deposited in anotherErosion – process by which earth particles are moved from one place and deposited in another –Wind –Water

20. 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 Landforms resulting from processes Landforms resulting from external processes

21. Minerals and Rocks MineralsMinerals –Naturally occurring –Crystalline structure –Inorganic –Solid Rocks – solid, cohesive, aggregate of one or more crystalline mineralsRocks – solid, cohesive, aggregate of one or more crystalline minerals –Igneous (granite, lava) –Sedimentary (limestone, sandstone) –Metamorphic (marble, slate)

22. Rock Cycle Cycle of creation, destruction, and metamorphosis. –Three major rock classifications: IgneousIgneous SedimentarySedimentary MetamorphicMetamorphic

23. Igneous Rock Granite, Pumice, Basalt Sedimentary Rock Shale, Sandstone, Limestone Metamorphic Rock Slate, Quartzite, Marble Magma (Molten Rock) Weathering Erosion Transport Deposition Internal Processes External Processes Heat,Pressure Heat,Pressure

25. Soil Complex mixture of … –eroded rock –mineral nutrients –decaying organic matter – water –air –micro-organisms Renewable resource –Weathering of rocks –Sedimentation –Decomposition of organic matter

26. Soils: Formation  Soil horizons  Soil profile O horizon Leaf litter A horizon Topsoil B horizon Subsoil C horizon Parent material Mature soil Young soil Regolith Bedrock Immature soil Humus

27. 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

28. 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)

29. Soil Properties  Infiltration  Leaching  Porosity Water High permeabilityLow permeability  Permeability

30. Soil Properties  Texture  Structure 100%clay Increasing percentage silt Increasing percentage clay 0 20 40 60 80 60 40 20 0 100%sand 80604020 100%silt Increasing percentage sand

31. 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 Gravel 2-64 mm Sand 0.05-2 mm Silt 0.002-0.05 mm Clay less than 0.002 mm Soil Texture Triangle

32. Properties of Soils with Different Textures TextureNutrientInfiltrationWater-HoldingAerationTilthCapacity ClayGoodPoorGoodPoorPoor SiltMediumMediumMediumMediumMedium SandPoorGoodPoorGoodGood Loam MediumMediumMediumMediumMedium Refer to Fig. 10-15 p. 215

33. Chemical Properties of Soil pH Fertility –20 minerals needed for plant growth –Major Nutrients (N-P-K) Nitrogen Phosphorus Potassium –Minor Nutrients Soil Tests

34. Soil Erosion The movement of soil components from one place to another by wind and water. Sheet erosion – water moves down a slope or across a field in a wide flowSheet erosion – water moves down a slope or across a field in a wide flow Rill erosion – surface water forms fast-flowing rivulets that cut channels in the soilRill erosion – surface water forms fast-flowing rivulets that cut channels in the soil Gully erosion – rivulets join together and cut channels wider and deeper until they become ditches and gullies.Gully erosion – rivulets join together and cut channels wider and deeper until they become ditches and gullies.

35. Areas of serious concern Areas of some concern Stable or nonvegetative areas Global Soil Erosion loss of soil organic matterloss of soil organic matter reduced ability to store waterreduced ability to store water increased use of fertilizerincreased use of fertilizer floodingflooding sedimentationsedimentation floodingflooding sedimentationsedimentation

36. Desertification Causes OvergrazingOvergrazing DeforestationDeforestation Surface miningSurface mining ErosionErosion SalinizationSalinization Soil compactionSoil compaction Consequences Worsening droughtWorsening drought FamineFamine Economic lossesEconomic losses Lower living standardsLower living standards Environmental refugeesEnvironmental refugeesConsequences Worsening droughtWorsening drought FamineFamine Economic lossesEconomic losses Lower living standardsLower living standards Environmental refugeesEnvironmental refugees Conversion of rangeland, rain-fed cropland, or irrigated cropland to desert-like land, with a drop in agricultural productivity of 10% or more.

37. Soil Degradation  Salinization - the accumulation of salt  Salinization - the accumulation of salt  Waterlogging – saturation of soil with irrigation water or excess precipitation so the water table rises close to the surface.  Waterlogging – saturation of soil with irrigation water or excess precipitation so the water table rises close to the surface. Evaporation Transpiration Evaporation Waterlogging Less permeable clay layer

38. Solutions: Soil Conservation  Conventional-tillage  Conservation tillage  Cropping methods  Windbreaks

39. Conventional tillage Crop cultivation method in which a planting surface is made by plowing land, breaking up the exposed soil, and then smoothing the surface.Crop cultivation method in which a planting surface is made by plowing land, breaking up the exposed soil, and then smoothing the surface.

40. Conservation tillage Crop cultivation in which soil is disturbed little (mini-mum tillage farming) or not at all (no-till farming) to reduce soil erosion, lower labor costs, and save energy.Crop cultivation in which soil is disturbed little (mini-mum tillage farming) or not at all (no-till farming) to reduce soil erosion, lower labor costs, and save energy.

41. Terracing

42. Contour planting and strip cropping

43. Alley cropping

44. Windbreaks

45. Soil Restoration Crop Rotation – planting a field with different crops from year to year to reduce soil nutrient depletion.

46. Soil Restoration Organic Fertilizers Animal manure –Improves soil structure –Adds organic nitrogen –Stimulates beneficial soil bacteria and fungi Green manure –Fresh and growing green vegetation Compost –Microorganisms break down organic matter in the presence of oxygen

47. Soil Restoration Commercial Inorganic Fertilizers Nitrogen, Phosphorus and Potassium –N, P, K AdvantagesAdvantages –Easily transported, stored, and applied DisadvantagesDisadvantages –Not adding humus –Reducing organic matter content –Lowering oxygen content –Supply only 2 or 3 of the more than 20 nutrients needed –Require large amounts –Release nitrous oxides