Transcript Figure 15-4
Chapter 15 Geology and Nonrenewable Mineral Resources Pangaea 18 simulation The Earth’s Major Tectonic Plates Figure 15-4 Geologic Processes 35 km (21 mi.) avg., 1,200˚C Crust 100 km (60 mi.) 200 km (120 mi.) Crust Low-velocity zone Structure of the Earth Mantle Lithosphere Solid Age of the earth?? 10 to 65km 2,900km 100 km (1,800 mi.) 3,700˚C Outer core (liquid) Core 200 km 5,200 km (3,100 mi.), 4,300˚C Inner core (solid) Asthenosphere (depth unknown) Spreading center Collision between two continents Ocean trench Oceanic crust Oceanic Subduction zone crust Continental crust Continental crust Material cools as Cold dense it reaches thematerial falls back outer mantle through mantle Mantle convection cell Two plates move towards each other. One is subducted back into the mantle on a falling convection current. Hot material rising through the mantle Mantle Hot outer core Inner core Fig. 15-3, p. 337 The Earth’s Major Tectonic Plates • The extremely slow movements of these plates cause them to grind into one another at convergent plate boundaries, move apart at divergent plate boundaries and slide past at LATERAL plate boundaries. Figure 15-4 Lateral movement Natural Hazards: Earthquakes Features Magnitude Liquefaction of recent sediments causes buildings of sink Landslides may occur on hilly ground Shock waves Epicenter Focus Two adjoining plates move laterally along the fault line Earth movements Cause flooding in Low-lying areas What is a mineral? • Elements come together to form minerals • General characteristics of minerals – – – – – 1.Natural ( not man made) 2.Inorganic 3.Crystalline 4.Solid 5.Constant chemical composition. Minerals and Rocks Rock Types Igneous Sedimentary Metamorphic Rock Cycle Figure 15-8 External Earth Processes Erosion-worn away and deposited Mechanical weathering Frost and salt wedging Chemical weathering Soils: Formation Soil horizons Soil profile Humus Immature soil O horizon Leaf litter A horizon Topsoil Regolith Bedrock B horizon Subsoil C horizon Young soil Parent material Mature soil Open-pit Mining • Machines dig holes and remove ores, sand, gravel, and stone. • Toxic groundwater can accumulate at the bottom. Figure 15-11 Contour Strip Mining • Used on hilly or mountainous terrain. • Unless the land is restored, a wall of dirt is left in front of a highly erodible bank called a highwall. Figure 15-13 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. Figure 15-14 Surface Mining Control and Reclamation Act Established 1977 Mine lands must be restored to premining conditions Taxes on mining companies to restore pre-1977 sites Limited success-Lobbying of officials have choked off funds for enforcement Environmental Effects of Mining Mineral Resources Disruption of land surface Subsidence Acid mine drainage Air pollution Storage and leakage of liquid mining waste-acids, cyanide, mercury Sludge Pharmaceutical plant Sludge Greenhouses Waste heat Fish farming Waste heat Oil refinery Surplus sulfur Local farmers Surplus natural gas Electric power plant Waste calcium sulfate Cement manufacturer Sulfuric acid producer Wallboard factory Area homes Fig. 15-19, p. 352 Rock lab guidelines • Go by the numbers on the white pieces of paper in the tray. VERY IMPORTANT • Know the category-Igneous, metamorphic, sedimentary • Grades based on how many names correctly identified. • Each number unique name. No two the same. • No talking between groups. • One free check PER GROUP Rock lab • Omit – Igneous: gabbro, andesite – Metamorphic: schist, quartizite – Sedimentary: siltstone, shale,rocksalt,rock gypsum, tufa, organic limestone. Will Durant Civilization exists by geological consent, subject to change without notice. End of chapter 15