Thars Gold in Them Thar Hills

1. Thars Gold in Them Thar Hills AP Environmental Science

2. Earth's three major concentric zones • Core • Mantle • asthenosphere • Lithosphere • Crust

3. Spreading center Collision between two continents Ocean trench Oceanic tectonic plate Oceanic tectonic plate Plate movement Plate movement Tectonic plate Oceanic crust Oceanic crust Subduction zone Continental crust Continental crust Material cools as it reaches the outer mantle Cold dense material falls back through mantle Hot material rising through the mantle Mantle convection cell Mantle Two plates move towards each other. One is subducted back into the mantle on a falling convection current. Hot outer core Inner core Fig. 15-3, p. 337

4. Three types of plate boundaries • Divergent plate boundaries • Plates move apart from one another • Convergent plate boundaries • Internal forces push two plates together • Transform faults • Plates slide and grind past one another along a fault line

5. Divergent plate boundaries

6. Convergent plate boundaries

7. Transform fault

11. Natural geologic hazards • Earthquakes • Volcanoes • Tsunamis

12. How tsunamis occur

13. External processes shaping the earth • Weathering • Physical or mechanical weathering • Chemical weathering • Biological weathering • Erosion • Flowing streams and rain • Wind • Glaciers • Mass wasting • Rockslides, landslides, mudslides

14. Rocks shaped by glaciers

15. Yosemite Valley shaped by a glacier

16. Valley of Fire in New Mexico created by lave seeping out of the ground

17. Three types of rock • Igneous • Granite, lava rock • Sedimentary • Sandstone, shale, dolomite, limestone, lignite, bituminous coal • Metamorphic • Anthracite, shale, marble

18. Igneous rock Forms below earth’s surface, when molten rock comes up from the upper mantle, cools, and hardens

19. Sedimentary rock Forms from sediments deposited in layers which accumulate over time – the weight and pressure “cements” these layers together

20. Metamorphic rock Forms when preexisting rock is subjected to high temperatures, high pressures, chemically active fluids, or a combination of these agents

21. Rock cycle • Interaction of physical and chemical processes • Recycles the earth three types of rocks • Slowest of earth’s cyclic processes • Concentrates the planet’s nonrenewable minerals • Without it we would not exist

23. Mineral resource – concentration of naturally occurring material in or on the Earth’s crust that can be extracted and processed into useful materials at an affordable cost

24. Nonrenewable Mineral Resources • Metallic mineral resources • Iron, copper, and aluminum • Nonmetallic mineral resources • Salt, gypsum, phosphates, water, and soil • Energy resources • Coal, oil, natural gas, and uranium

25. Ore – rock containing enough of one or more metallic minerals to be mined profitably High-grade ore vs. low-grade ore Reserves – identified resources from which a usable nonrenewable mineral can be extracted profitably at current prices

26. Global Outlook: Mineral Resource Distribution • United States, Canada, Russia, South Africa, and Australia supply most of the nonrenewable mineral resources used by modern societies • United States, Germany, and Russia consume about 75% of the world’s most widely used metals • Japan virtually has no metal resources

27. Nonrenewable Mineral Resources in the United States • Depleted some of its metal resources – lead, aluminum, and iron • Depends on imports of 24 of its 42 most important nonrenewable mineral resources • No manganese, cobalt, chromium, and platinum reserves –essential for economy and military (without these there are no planes, jet engines, automobiles, satellites, sophisticated weapons, and home appliances)

28. SUPPLIES OF MINERAL RESOURCES • The future supply of a resource depends on its affordable supply and how rapidly that supply is used. • A rising price for a scarce mineral resource can increase supplies and encourage more efficient use.

29. SUPPLIES OF MINERAL RESOURCES • Depletion curves for a renewable resource using three sets of assumptions. • Dashed vertical lines represent times when 80% depletion occurs.

30. Ores (result of several internal and external geologic processes) • Plate tectonics • Magma • Hydrothermal process • Manganese nodules

31. Manganese Nodules • Potato-size • Contain 30 – 40% manganese by weight • Also contain iron, copper, and nickel • Cover about 25 – 50% of the Pacific Ocean floor • Can be sucked up or scooped up – what are the environmental impacts?

32. How are buried mineral deposits found? • Remote sensing – aerial photos and satellite images • Planes with radiation measuring equipment and magnetometer • Drilling deep wells • Sensors in already dug wells • Seismic surveys • Chemical analysis

33. Mining Extraction Techniques • Surface mining – equipment strips away the overburden of soil and rock and discards as spoil • Subsurface mining – underground • In-situ leaching –flush out desired mineral

34. Bucket-wheel Excavator

35. Types of Surface Mining • Open-pit mining • Dredging • Area strip mining • Contour strip mining • Mountaintop removal

36. Open-pit diamond mine

37. Open-pit diamond mine in Canada – have you seen Ice Road Truckers

38. Open-pit copper mine in Silver City, New Mexico

39. Strip mining

40. Strip mining

41. Contour strip mining for coal

42. Dredging

43. Mountaintop Removal • Machinery removes the tops of mountains to expose coal. • The resulting waste rock and dirt are dumped into the streams and valleys below.

44. Subsurface mining disturbs less than one-tenth as much land as surface mining and usually produces less waste material.

45. Hazards of Subsurface Mining • Collapse of roofs and walls • Explosions of dust and natural gas • Lung diseases

46. Hazards of mining coal – dust of coal can ignite

47. In-situ leaching – small holes are drilled and a water-based chemical solvent is used to flush out desired minerals

48. In-situ Leaching • Waste rock is minimal • Safer for miners • Less expensive • Shorter lead times to production • Less surface ground disturbance • Less required remediation • Toxic chemicals enter groundwater supply

49. Environmental Impacts • Scarring and disruption of the land surface • Collapse of land above underground mines • Wind- or water-caused erosion of toxin laced mining water • Acid mine drainage • Emissions of toxic chemicals into the atmosphere • Exposure of wildlife to toxic mining waste

50. Natural Capital Degradation Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources Steps Environmental effects Mining Disturbed land; mining accidents; health hazards, mine waste dumping, oil spills and blowouts; noise; ugliness; heat Exploration, extraction Processing Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat Transportation, purification, manufacturing Use Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat Transportation or transmission to individual user, eventual use, and discarding