The Dynamic Planet Natural Processes or Natural Disasters The earth is a dynamic planet with complex internal and external flows of energy that produce natural processes that are supposed to happen and have been for billions of years Natural disasters occur when the earth s natural processes concentrate energy and then release it causing property damage and or loss of life Origin of the Solar System Rotating cloud of dust and gas gathers due to gravitational forces Rotating mass contracts and flattens with most of the mass in the center The center contracts into a ball of hot gas and dust which ignites to form the sun Accretion resulted in planet formation whereby the gases outside of the sun condensed into solid materials Solar Energy The Sun is the Power House for the entire Solar System It is a fairly typical star that is not burning but is fusing together Hydrogen to form Helium In so doing it releases energy in vast quantities Solar energy drives the hydrologic cycle Uneven distribution of solar energy causes severe weather Earth s Internal Heat Three Sources of the Earth s Internal Energy Heat Gravitational collapse Impact Energy Radioactive decay End Result Early Earth is hot hot hot Density Differentiation of the Earth produces Earths internal structure Crust Mantle Core Earth Structure The earth today is the product of over 4 5 billion years of differentiation into layers of varying density The 8 most abundant elements in the earth are iron Fe sodium Na oxygen O calcium Ca silicon Si aluminum Al and magnesium Mg potassium K Earth Structure Density Stratified Layers Earth s Core The earth s core is composed of two parts the inner core and the outer core The inner core is SOLID iron Fe and nickel Ni and the outer core is LIQUID Fe and Ni Mantle The mantle extends from roughly 50 2900km below the earth s surface and is primarily composed of Fe Mg rich silicates minerals Crust Is composed of two types Oceanic Crust is 7 10 km thick primarily made of Fe and Mg rich silicate minerals MAFIC low Si and O high Fe and Mg Continental Crust is 20 70km thick primarily made of Si and O rich minerals FELSIC high Si and O low Fe and Mg Crust vs Mantle The mantle contains MORE Fe and Mg than the oceanic crust and the oceanic crust contains MORE Fe and Mg than the continental crust Because Fe and Mg are DENSER elements the mantle is denser than the oceanic crust and the oceanic crust is denser than the continental crust Density mass volume Earth Structure Layers of Different Strengths The crust and the upper part of the mantle is called the LITHOSPHERE and it is RIGID BRITTLE and behaves ELASTICALLY The part of the mantle directly below the lithosphere is termed the ASTHENOSPHERE which behaves like a PLASTIC a solid that flows Plate Tectonic Theory 12 large plates 12 small plates Mantle convection drives plate motion Heat Sources Original heat from formation of the Earth radioactive decay of U Th and K in the core and mantle Plate Velocity up to 17cm year Types of Plate Boundaries Convergent Boundaries Divergent Boundaries Transform Boundaries Moving plates cause EQ s and volcanoes
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