1. Geology: Processes, Hazards, and Soils G. Tyler Miller’s Living in the Environment G. Tyler Miller’s Living in the Environment

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

3. 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

4. Continental Drift  Continents had once been joined to form a single supercontinent (Pangaea)  Developed by Alfred Wegener  1) Pangaea begin to break apart 200 million years ago  2) Forms the present landmasses

5. Breakup of Pangaea

6. Evidence for Continental Drift Continental Puzzle Matching Fossils –Fossil organisms found on different landmasses Rock Types and Structures –Same rocks on one coastline, and then reppear on a landmass across the ocean Ancient Climates –Glaciers

7. Matching Mountain Ranges

8. Glacier Evidence

9. Plate Tectonics Wegener could NOT explain what made the continents move A New Theory Emerges…. Plate Tectonics!

10. Plate Tectonics  Theory explaining the movement of tectonic plates and the processes that occur at their boundaries.  Lithosphere  Uppermost mantle + crust = strong, rigid layer  Asthenosphere  Molten rock, lower mantle  Lithosphere moves atop asthenosphere

11. Causes of Plate Motion Convection –Driving force for plate movement –Motion of matter from changes in temperature

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

13. Lithosphere Asthenosphere Two plates move apart/diverge (spreading centers) Divergent Boundary

14. Lithosphere Trench Volcanic island arc Asthenosphere Risingmagma Subductionzone Two plates move together/converge. Convergent Boundary

15. Transform fault Lithosphere Asthenosphere Transform Faults Two plates grind past each other without the production or destruction of the lithosphere.

16. VolcanoesEarthquakes Ring of Fire

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

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

19. Natural Hazards: Volcanic Eruptions Tephra (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

20. 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

21. 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

22. 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)

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

25. IGNEOUS SEDIMENTARY METAMORPHIC Weathering, Erosion, Compaction, Cementation Heat & Pressure Weathering, Erosion, Compaction, Cementation Heat and Pressure Melting, Solidification

26. 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

27. 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

28. 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. 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. 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. Soil Texture Soil texture is determined by particle size

34. Particle Size Largest: Sand Medium: Silt Small: Clay

35. Sand Large particles Coarse texture Does NOT hold water well

36. Silt Medium-sized particles (between sand and clay) Fine texture Responsible for most productivity (agriculture)

37. Clay Smallest particles Very fine texture Holds nutrients and water well

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

39. Porosity vs. Permeability Porosity Permeability - Percentage of pore spaces - Determines how much groundwater can be stored -Ability to transmit water through connected pore spaces -Permeable: Water CAN pass through -Impermeable: Water CAN’T pass through

40. Permeability 1.Gravel: High permeability 1.Sand: High/Medium permeability 1.Clay: Low permeability 1.Solid Rock (Bedrock): Impermeable

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

44. 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.

45. 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

46. Areas of serious concern Areas of some concern Stable or nonvegetative areas

47. 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.

48. 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

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

50. 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.

51. 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.

52. Terracing

53. Contour planting and strip cropping

54. Windbreaks

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

56. 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

57. 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