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EARTH SYSTEMS Chapter 8 Part 1 – Tectonic Cycle STNT 35 Your questions and key for your test Case Study – Hybrid Vehicles 1. What is the benefit of hybrid vehicles? 2. What are the drawbacks of hybrid vehicles? 3. What is believed to be the limiting factor for the production of hybrid vehicles? Explain. 4. What is the environmental concern in addition to the limiting factors for hybrid vehicles? Explain. 5. What are the environmental problems of surface mining for the metals needed? When? How? • Originally the earth was a molten sphere with some debris added from the sun formation. • As the molten material cooled, the elements separated into layers: heavier ones sinking, lighter ones rising. Elements and Minerals? • Nearly all the elements on earth are as old as the planet. • Distribution of the elements and minerals. Earth Formation Vertical Zonation Innermost zone Mantle • Convection cells • Asthenosphere • Solid Upper layer Lithosphere • Large and small plates Crust Earth’s Layers • A wedge from Earth would cover the width of the U.S. Earth’s Geologic Cycle Three major processes of the geologic cycle • Tectonic cycle • Rock cycle • Soil formation Convection and Hot Spots High temperature of Earth’s outer core and mantle convection cells • Radioactive decay Result of the high temperature • Plumes of hot magma • Hot spots • Convection cells Results of convection cells Theory of Plate Tectonics The earth’s lithosphere is divided into plates, most of which are in constant motion. Tectonics Cycle All the processes that build up and break down the lithosphere. Evidences? Add to Laws Tectonic Cycle Two types of plates of the lithosphere. Movement of the plates? Seafloor spreading. Subduction Consequences of Plate Movement Geologic time scale. Results of continental drift? Current Era/Period Results of plates moving continents to different areas or breaking continents apart? • Volcanoes • Earthquakes • Seafloor spreading • Mountain formation Volcanoes • Most along plate boundaries. • A vent in Earth’s surface that emits ash, gases and molten lava. Natural source of: • CO2 • Sulfur • Particulates • Metals from the core Islands still forming The Hawaiian Islands Volcanic Arc Iceland Volcanic Eruption • Iceland volcanic eruption in 2010: – Suspended air travel in many parts of Europe. – Ash contained silicon dioxide which is harmful to airplane engines. Plate Movement Simulation • Purpose – To simulate the three types of tectonic plate movements. • Materials – Oreo Double Stuff Cookie – Upper cookie is the lithosphere – Creamy filling is asthenosphere – Lower cookie is the lower mantle Procedure • Carefully remove the upper cookie (a twisting motion is required) • Slide the upper cookie over the creamy filling to simulate motion of a rigid lithospheric plate over the softer asthenosphere. • Break the upper cookie in half. – Listen to the sound it makes when you break it. – What does that sound represent? Types of Tectonic Plate Contact Divergent plate boundaries • Oceanic and oceanic plate contact • Continental and continental plate conact Simulation of Divergent Plate Boundary • Push down on the two broken cookie halves and slide them apart. • Notice that the creamy filling between the two broken “plates” may tend to flow upward, similar to the rising, decompression and partial melting of hot asthenosphere at sea floor spreading and continental rifts. Convergent Plate Contact Convergent plate contact. • Oceanic and continental plates • Continental and continental plates • Oceanic and oceanic Simulation of Convergent Plate Boundary • Push one cookie piece beneath the other. • Notice what happens to each cookie piece. • What is this movement called? • What plates will produce this movement? Transform Fault Description • Fault • Fault zone Results Simulation of Transform Plate Boundary • Slide the two cookie pieces laterally past one another over the creamy filling. • You can feel and hear the “plates” do not slide smoothly past one another but rather stick and then let go, stick and then let go. • The cracking you hear each time is like an earthquake occurring along the San Andreas Fault. Do the Math • Los Angles is 630km (380mi) southwest of San Francisco. The plate under LA is moving 36 mm/year toward San Francisco. How long before they are side by side? Time = distance rate Add to your formula page Earthquakes • Internal geological process from vibrations from plate movements. – Releasing energy causing a shift or break in the earth’s crust. • • • • Focus Epicenter Seismic waves. Measurement Richter Scale • Charles Richter – devised the seismograph • • • • • • Insignificant – <than 4 Minor – 4.0 – 4.9 Damaging – 5.0 – 5.9 Destructive – 6.0 – 6.9 Major – 7.0 – 7.9 Great – Over 8.0 Haiti earthquake in 2010 Chili Largest earthquake in 1960 7.0 9.5 U.S. Earthquake Risk Global Earthquake Risk Tsunami • • • • Definition Cause Formation Role of coral reefs, mangrove forests and other wetlands. Largest in 2004 by an earthquake ( 9.1) in the Indian Ocean affecting Indonesia, Thailand, Sri Lanka, South India and East Africa. Chapter 8 Part 2 Geologic Cycle – 2nd Process Rock cycle • Constant formation and destruction of rock. • Slowest of all Earth’s cycles Difference between a rock and a minerals? Rock Cycle • Relationship between magna and rock. • Three ways rocks are formed. • Three types of rocks. Classification of Rocks • Formation of each type of rock. – Igneous – Sedimentary – Metamorphic Weathering Define weathering. Explain physical and biological weathering. Physical Biological Chemical Weathering Explain chemical weathering. • CO2 + H2O H2CO3 – Carbonic acid. – Dissolves limestone. • Anthropogenic – SO2 + H2O H2SO4 – Acid rain – Sulfuric Acid Erosion • Define erosion. • Explain how erosion is different from weathering. • Explain the 2 mechanisms causing erosion. • What is deposition? • Identify some natural causes of erosion. • Identify some anthropogenic causes of erosion. Soil Formation 3rd Process • Soil – Mixture of geologic and organic components • Functions of soil. The Formation of Soil • From hundreds to thousands of years. – Result of weathering of rocks and gradual accumulation of detritus from the biosphere. – Wind and erosion – From top down and bottom up – Young soil, mature soil, old soil Factors Determining Properties of Soil How these factors determine the properties of soil: • Parent material • Climate • Topography • Organisms • Time Soil Horizons (layers) • • • • • O horizon A horizon B horizon C horizon E horizon Physical Properties of Soil • Sand, silt and clay are mineral particles of different sizes. • Texture of soil – % of sand, silt, clay – Sum always 100% Soil Texture Chart • Determine the texture of soil that is 60% silt, 30% sand and 10% clay. Physical Properties of Soil Porosity • How much space is located between the particles that contains air, water Permeability of soil • How quickly it drains - Depends on its texture – Sand – Silt – Clay – What is the best agricultural soil? Why? • What is the problem associated with very sandy soils? • Why are landfills lined with clay? Chemical Properties of Soil • Clay particles contribute the most to the chemical properties of soil – Cations – positively charged mineral ions – Clay particles are negatively charged – CEC cation exchange capacity • What is the CEC most desirable for agriculture and why? • Tradeoff between CEC and permeability Chemical Properties – Acids and Bases • Soil bases – Calcium, magnesium, potassium, sodium • Soil acids – Aluminum, hydrogen • Which is better for plant growth? Why? • Base saturation Biological Properties of Soil • Common organisms in the soil • Rodents/earthworms • Snails/slugs • Soil bacteria • Classification of most organisms in the soil. – Function Soil Degradation and Erosion • Soil degradation – Loss of some or all of the ability of the soil to support plant growth. • Causes – Compaction – Soil drying • Major cause – soil erosion • Which horizon contains the topsoil? • Why is topsoil loss so damaging? Mineral Resources • Crustal abundance • Four elements that make up 88% of the Earth’s crust. • Ore – Concentrated abundance of minerals from which economically valuable material can be extracted. – May contain metals or not • Metals. Reserve – known quantity of the resource that can economically recovered. Mineral Resources • Mining. – Extraction from the earth of the ore – Separation desired materials out of the ore • Two types of mining – Surface mining – Subsurface mining • Mineral resource or mineral deposit – Concentration of a natural substance in crust that can be extracted and processed into useful products at an affordable cost. Surface Mining • Four types of surface mining: • Strip mining – Removal of strips of soil and rock to expose ore close to the surface. – Use often to mine coal and sand. • Mining spoils or tailings. Open-pit mining • Creation of a large pit or hole in the ground. • When the resource is close to the surface but extend beneath the surface both horizontally and vertically. Kennecott Bingham Canyon Mine - Utah • Copper mine • One of the largest open-pit mines in the world. Mountaintop Removal • Removal of the entire top of a mountain with explosives. – Generally coal mining – In the Appalachian area, 470 of the largest mountains are gone. – Tailings often erode or leach into mountain streams. Placer Mining • Process of looking for metals and precious stones in river sediments. • Use of river water to separate the ore. • Diamonds, gold Illegal tropical placer mining. Using water cannons to wash entire hillside into collection boxes. Subsurface Mining • Removal of deep deposits. • Horizontal and vertical shafts. Comparison of Surface and Subsurface Mining Advantages and Disadvantages of Mining • Advantages of mining. – Economics – Jobs – Resources for manufacturing • Disadvantages of mining. – – – – – Disturbance of soil Degradation/fragmentation of habitats Erosion Soil, air and water pollution Subsurface – dangerous to workers/ lung diseases Distribution of Mineral Resources • The most – U.S. Canada, Russia, South Africa, Australia • South Africa – Nearly self-sufficient in world’s key resources. – Largest producer of • Gold • Chromium • Platinum Nonrenewable Minerals • Supply • Actual or potential supply • Rate of use • • • Economically depleted • When it costs more than it is worth to find, extract, transport and process the remaining deposits. Recourses when the supply is economically depleted • Reuse or recycle • Waste less • Use less • Find a substitute • Do without Depletion of Nonrenewable Mineral Resources. • Depletion time • Time it takes to use up 80% or the reserves at a given rate of use. • Dashed vertical lines show when 80% depletion occurs. Mining Laws • Early mining laws focused primarily on promoting economic development. • Later laws were concerned with worker safety and environmental protection. U.S. General Mining Law of 1872 • Governs hardrock mining (gold, copper, silver, etc.) on America's public lands. • Congress was trying to encourage settlement of the American West by offering free minerals and land to those who were willing to settle out West and mine. • Currently, mining companies are allowed to buy up America's public lands for $5 or less per acre. Add laws to your binder. • Additionally, the mining industry, unlike coal and oil companies, is not required to pay production royalties or rental fees for the use of public land, and there are few environmental standards or requirements governing cleanup. • In fact, hardrock mining pours more toxics into the environment than any other industry in the country . • The federal government currently interprets the 1872 Mining Law as mandating that mining is the highest and best use for public lands. SMCRA • Surface Mining Control and Reclamation Act. – Regulates surface mining of coal and the surface effects of subsurface coal mining. – Act mandates that land be minimally disturbed during the mining process and reclaimed after mining is completed. – Requires restoration of abandoned mines.