Geological Catastrophes Midterm Review

Geological Catastrophes Midterm Review - 23:14 o o...

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Geological Catastrophes Review 23:14 The layering of the Earth is characterized by: Differences in density o Less dense materials are on top of more dense materials o Crust overlies mantle By differences in strength o Lithosphere overlies asthenosphere—lithosphere is rigid (solid rock) as  opposed to the asthenosphere which is fluid like (plastic rock) and then  mesosphere is solid mantle below asthenosphere o Mesosphere asthenosphere lithosphere hydrosphere atmosphere Center of Earth: Iron-rich core ~7,000 km in diameter o Inner core is solid and 2,450 km in diameter o Outer core is liquid and has viscous convection currents, responsible for  Earth’s magnetic field Surrounding core is Earth’s mantle, 2,900 km thick o Stony in composition (like chondritic meteorites) o 83% of Earth’s volume, 67% of Earth’s mass Low-density elements have been ‘sweated’ out of the mantle to form the crust,  atmosphere and oceans Earth’s history: Earth is 4.6 billion years old Earth began as aggregating mass of gases and particles  Processes of planet formation created huge amounts of heat o Impact energy 
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o Decay of radioactive elements o Gravitational collapse energy o Differentiation into layers: As temperature rose above 1,000 centigrade, iron melted  Liquid iron is denser than remaining rock, so sank toward center of  Earth and formed inner and outer core Release of gravitational energy produced more heat—remaining rock  melted, allowing low-density material to rise  Low-density material formed crust, oceans, and atmosphere 3.9 billion years ago: large oceans, small continents 3.5 billion years ago: life (photosynthetic bacteria) 2.5 billion years ago: large continents 1.5 billion years ago: plate tectonics Where does energy to drive catastrophes originate? Impacts of extraterrestrial objects (meteors/comets) Gravitation—both internal (collapse) and external (tides) Earth’s internal heat— latent heat  from formation and  radioactive decay Solar radiation World Disaster Fatalities: There are more people killed in poorer nations then in industrial countries amount of people killed in natural disasters in increasing order—industrial  nations developing nations poorest nations
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2009- Was the mildest year for natural disasters!!! World Disaster Damage ($$$): Natural disasters cost industrial nations more money than poorer countries o Amt. of money caused by natural disasters in increasing order for each  type of society—poorest nations developing nations  industrial nations The number of earthquakes is NOT increasing, the Population IS!!!
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