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ch12_Geology - Chapter 12 Mineral and Soil Resources...

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Unformatted text preview: Chapter 12 Mineral and Soil Resources Mineral Rock Cycle Three Types of Rocks Igneous – produce in the Earths interior Scoria, Pumice, Obsidian Sedimentary – erosion and weathering Limestone, Salt, Sandstone Metamorphic – high heat, pressure and chemically active fluids Marble, Soapstone, Slate Copper Basin, Tennessee Copper 19th century Copper mining Open­air smelters Trees cut to provide wood for smelters Sulfur dioxide formed ­→ acid precipitation Ecological ruin Copper Basin, Tennessee 1970s: replanting techniques Plants had to be reestablished: why? Area improving Return of forest will take decades Basic Geology Basic Lithosphere Earth’s outermost layer Seven large plates Floats on asthenosphere The plates move: plate tectonics Wegener’s Evidence Wegener’s Evidence Fit of the continents Rock type & structural similarities Fossil evidence Paleomagnetism Plate Tectonics Plate Plate boundary Where two plates meet Intense geologic activity Earthquakes, volcanoes Formation of mountains Atlantic Ocean growing: separating plates Plates & Boundaries Plates Plate Boundaries Boundaries Volcanoes Volcanoes Movement of tectonic plates on hot soft rock Heat melts rock → magma Lava: magma at surface Environmental impacts of eruptions? Earthquakes Earthquakes Rocks in lithosphere shift or break Energy released as seismic waves Usually along fault Focus: where quake begins Epicenter: directly above focus More than 1 million quakes per year Measure using Richter scale Side Effects of Earthquakes Side Landslides Tsunamis Giant sea waves Indian Ocean 2004 Waves over 30 m More than 225,000 died Important Minerals Important Sulfides: contain sulfur Oxides: contain oxygen Metals Malleable, lustrous, conductors Iron, aluminum, copper Nonmetallic minerals Ore Rock with valuable mineral Minerals & Their Uses Minerals Extracting Minerals Extracting Locate deposit Analyze mineral composition Mine for minerals: many different ways Process mineral Make product Surface Mining Surface Near the surface Less expensive Overburden removed Open­pit Dig quarry Iron, copper, gravel Surface Mining Strip mining Dig trench to extract mineral Dig parallel trench Cover old trench with new overburden Spoil bank Subsurface Mining Subsurface Minerals deep in ground Less land disturbance More expensive More hazardous Shaft mine Direct vertical shaft Coal Subsurface Mining Slope mine Slanting passage Ore hauled in cars Processing Minerals Processing Smelting Melt ore to separate impurities from desired mineral Blast furnace Slag disposed of Mining & The Environment Mining Disturbs land Land prone to erosion → further damage Uses a lot of water Contaminated streams Acid­mine drainage Impacts of Refining Impacts About 80% of mined ore made of impurities Tailings Waste left behind Left in piles Toxic Impacts of Refining Impacts Smelting emits pollutants Acid precipitation Hazardous solid and liquid wastes A lot of energyrequired Restoration of Mining Lands Restoration When mine no longer profitable Prevents further degradation Filling in and grading the area Planting vegetation Surface Mining Control & Reclamation Act of 1977 Lands mined for coal Soil: What Is It? Soil: More than just dirt! Uppermost layer of Earth’s crust Mineral and organic matter Living organisms We depend on it: how? Soil Formation Soil Formed from parent material Biological, chemical and physical weathering processes Continuous process Topography plays a role: how? Takes a long time Soil Composition Soil Four main parts Mineral particles Main component From parent material Provides anchorage and minerals Organic matter Living or formerly living matter Humus Air Water Soil Organisms Soil Soil is alive! Plant roots, insects, earthworms, moles, etc… Bacteria most numerous Fungi, algae, protozoa Provide ecosystem services: examples? Soil Organisms Soil Decomposition Decomposition Nutrient cycling Pathway of nutrient minerals or elements Sign of balanced ecosystem Soil Problems Soil Our activities cause many problems Soil erosion Mineral depletion Soil pollution Sustainable soil use Wise use of soil resources Keep soil productive for the future Soil Erosion Soil Movement of soil Natural process Accelerated today Water, wind Major effects Loss of soil fertility Soil cannot retain as much water Runoff into bodies of water Soil Erosion Poor soil management Agriculture, road building, logging Plant cover limits erosion Soil Pollution Soil Physical or chemical change in soil Adversely affects health of organisms Some from fertilizers, pesticides Salinization Result of irrigation Can render soil useless Soil Conservation Soil Only 11% world’s soil suitable for agriculture Much already degraded Conservation Tillage Conservation Residues from previous crops left in soil Reduces erosion up to 70% More than 1/3 U.S. cropland Soil has more organic material Drawbacks? Crop Rotation Crop Planting a series crops in the same field over a period of years Decreases insect damage Reduces erosion Rotated crops depend on where you farm Terracing Terracing Used on very steep slopes Like stairs Very expensive! Other Methods Other Contour plowing Farm with the natural contours of the land Strip cropping Strips of differing crops Soil Reclamation Soil Badly eroded land Prevent further erosion Seed bare ground Plant shelterbelts Restore soil fertility Soil must recover first Restrict farming? Case Study: Industrial Ecosystems Ecosystems Industrial ecology Efficient use of resources “Wastes” are potential products Mimic natural ecosystems Kalundborg, Denmark Link different industries Kalundborg, Denmark Kalundborg, Case Study: Industrial Case Ecosystems Ecosystems Takes many years to develop Economy and environment benefit: how? ...
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