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Principles of Environmental Science Inquiry and Applications Third Edition Cunningham • Cunningham Chapter 11 Lecture Outlines* *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Outline: • • • • • • Tectonic Processes Minerals and Rocks Economic Geology and Mineralogy Strategic Resources Environmental Effects of Resource Extraction Mining - Restoration Conserving Geologic Resources Geologic Hazards 2 A DYNAMIC PLANET • A Layered Sphere Core - Interior composed of dense, intensely hot metal. Generates magnetic field enveloping the earth. Mantle - Hot, pliable layer surrounding the core. Less dense than core. Crust - Cool, lightweight, brittle outermost layer. Floats on top of mantle. 3 A Layered Sphere 4 Tectonic Processes 5 Tectonic Processes • Upper layer of mantle contains convection currents that break overlaying crust into a mosaic of tectonic plates. Slide slowly across earth’s surface. - Ocean basins form where continents crack and pull apart. - Magma forced up through cracks in oceanic crust form mid-oceanic ridges. 6 Tectonic Processes 7 Tectonic Processes Cont’d • Earthquakes are caused by grinding and jerking as plates slide past each other. Mountain ranges pushed up at the margins of colliding plates. - When an oceanic plate collides with a continental landmass, the continental plate will ride up over the seafloor and the oceanic plate will subduct down into the mantle. Deep ocean trenches mark subduction zones. 8 Pangea • Geologists suggest that several times in earth’s history most, or all, of the continents gathered to form a single super-continent, Pangea, surrounded by a single global ocean. 9 Extinctions Almost all professional football players are still alive. 4% of all human beings that have ever lived are still alive. What percent of all species that have ever lived are still alive? 0.1%; thus 99.9 % are extinct. Looking ahead, things look numerically bad for humans: chances are that we will go extinct. What is extinction? => Termination of a lineage. What are the units of extinction? Genus Family? Do we determine extinction of a genus by the last remaining species that makes up that genus? What happens if 99% of the genus goes extinct and one "hanger-on" last millions of more years? No solution to the problem, these are the sorts of biases that are inherent in tabulating higher-level phenomena. What can we say about adaptation and extinction rates? Is extinction due to: Bad luck or Bad genes? As to the causes of extinction here are some questions to "ask" the fossil record: intrinsic/extrinsic: was extinction due to a characteristic of the organism (intrinsic) or of the physical environment (extrinsic)? Was extinction due to competition (mutituberculates and rodents) or was it due to major events like sea level changes or asteroid impact? One "asks" the fossil record by looking at the data. 10 • Dinosaurs, along with an estimated 70 percent of all life on Earth, are believed to have gone extinct 65 million years ago as a result of a series of dramatic temperature changes. What killed the dinosaurs? Geologists and paleontologists often entertain the idea of a large asteroid or comet impacting the Earth as the culprit. • Besides the firestorms, tidal waves, earthquakes, and hurricane winds such an impact would generate, the debris thrown into the atmosphere would have a serious global environmental impact -creating extended periods of darkness, low temperatures, and acid rains. This picture shows the "meteor crater" in arizona which is 180 meters deep and 1.2 km in diameter with an eroded rim standing 30-60 m high. this crater is believed to have been made 50,000 years ago by a 46-meter wide meteorite composed of nickel-iron rock. 11 Extinction Timelines 12 GEOLOGIC HAZARDS • Earthquakes - Sudden movements of the earth’s crust that occur along faults where one rock mass slides past another. Gradual movement - creep. - When friction prevents creep, stress builds up until eventually released with a sudden jerk. Frequently occur along subduction zones. Tsunami - Seismic sea swells. 13 14 15 16 17 18 Country where deaths occurred Deaths Injured Missing Displaced 1 Confirmed Estimated 130,736 167,736 — 35,322 35,322 21,411 India 12,405 18,045 — 5,640 647,599 Thailand 5,395 8,212 8,457 2,817 7,000 Somalia 78 289 — — 5,000 Myanmar (Burma) 61 400-600 45 200 3,200 Maldives 82 108 — 26 15,000+ Malaysia 68– 69 75 299 6 — Tanzania 10 13 — — — Seychelles 3 3 57 — 200 Bangladesh 2 2 — — — South Africa 2 2 — — — Yemen 2 2 — — — Kenya 1 1 2 — — Madagascar — — — — 1,000+ Total ~184,168 ~230,210 ~125,000 ~45,752 ~1.69 million Indonesia Sri Lanka 2 3 4 37,063 500,000+ 516,150 edit 19 Volcanoes • Volcanoes and undersea magma vents are the sources of most of the earth’s crust. Many of world’s fertile soils are weathered volcanic material. - Human / Environmental Dangers Volcanic Ash Mudslides Sulfur Emissions 20 21 22 Volcanic ash from Pinatubo Volcano in the Philippines partly buries this village. The great 1991 eruption of Pinatubo was the second largest in the world during the 20th Century. 23 Floods • • • Excess water that overflows stream banks and covers adjacent land. Biggest economic loss is usually contamination, not direct property losses. - Carpet, furniture, drywall, etc. Many human activities increase both severity and frequency of floods. - Soil compaction Floodplains often help mitigate flooding. Usually flat, fertile, and easily farmed. - Flood control structures have separated floodplains from rivers. Flood Control Governmental air of flooding victims seems to have encouraged building on floodplains. 24 Floods Cont’d • • Floodplains often help mitigate flooding. Usually flat, fertile, and easily farmed. - Flood control structures have separated floodplains from rivers. Flood Control Governmental air of flooding victims seems to have encouraged building on floodplains. 25 Erosion • Landslides A general term for rapid down-slope movement of soil or rock. - Many human activities such as forest clearing and building homes on steep, unstable slopes increase both frequency and damage done by landslides. Barrier Islands Stand between mainland and open sea. Contain many of world’s sandy beaches. - Many people place a high value on the view and beach access, and thus these are highly prized areas to build structures. Assume modern technology will provide protection. 26 ECONOMIC GEOLOGY AND MINERALOGY • Metals Metals consumed in greatest quantity by world industry (metric tons annually): - Iron (740 million) - Aluminum (40 million) - Manganese (22.4 million) - Copper and Chromium (8 million ea) - Nickel (0.7 million) 27 Non-Metal Mineral Resources • • • • Sand and Gravel Brick and concrete construction, paving, sandblasting and glass production. Limestone Concrete and building stone Evaporites Gypsum and Potash Sulfur Sulfuric Acid 28 Strategic Metals and Minerals • Durable, highly valuable, and easily portable, gemstones and precious metals have been a way to store and transport wealth. These valuable materials have bankrolled despots, criminal gangs, and terrorism in many countries. Much of the illegal trade ends up in the $100 billion per year global jewelry trade, two-thirds of which sells in the U.S. 29 Strategic Metals and Minerals 30 ENVIRONMENTAL EFFECTS OF RESOURCE EXTRACTION • Mining Placer Mining - Hydraulically washing out metals deposited in streambed gravel. - Destroys streambeds and fills water with suspended solids. Strip-Mining or Open-Pit Mining - Large scars on land surface. - Tailings Toxic runoff 31 Strip mines 32 Mining • Underground Mining Very Dangerous - Gas - Inhaling Particulate Matter - Tunnel Collapse 33 Restoration • Surface Mining Control and Reclamation Act (1977) requires better restoration of stripmined lands, especially if land classed as prime farmland. Difficult and expensive. - Often more than $10,000.00 per hectare. 50% of U.S. coal is strip-mined. 34 Processing • Metals are extracted from ores by heating or treatment with chemical solvents. Smelting - Roasting ore to release metals. - Major source of air pollution. Heap-Leach Extraction - Crushed ore piled in large heaps and sprayed with a dilute alkaline cyanide solution which percolates through the pile to dissolve the gold. - Effluent left behind in ponds. 35 CONSERVING GEOLOGIC RESOURCES • Recycling Aluminum must be extracted from bauxite by electrolysis. - Recycling waste aluminum consumes one-twentieth the energy of extraction from raw ore. Nearly two-thirds of all aluminum beverage cans in U.S. are recycled. Other metals commonly recycled: - Platinum, gold, copper, lead, iron, steel. 36 Substituting New Materials For Old • Reduce metal consumption by using new materials or new technologies. Plastic pipes in place of metal pipes. Fiber-optics in place of metal wires. Metal alloys in place of traditional steel. Ceramics! 37