GEOS 212 1st Edition Lecture 3 Outline of Last Lecture 1 Layering of Earth 1 Crust Mantle Core chemistry versus 2 Lithosphere Asthenosphere Rest of Mantle Outer Core Inner Core mechanical properties 2 Continent versus Ocean Continental crust versus Oceanic crust mantle lithosphere asthenosphere draw diagram 3 Plate Tectonics explains opening and closing of ocean basins growth and shrinking of plates movement of plates and most earthquakes and volcanoes 4 Plate tectonics plates crust uppermost mantle 100km total are rigid and move over a very weak but not molten asthenosphere 5 Plate Boundaries Divergent Convergent Transform 6 Divergent Boundaries aka Spreading Centers Mid Ocean Ridges are where new plate is created 5cm yr sit 2km above rest of seafloor because they are warm 7 Diagram of spreading centers how oceanic crust is made 8 Animation of spreading centers 9 Video of ocean floor at spreading center height of spreading center length of spreading center water temperature big surprise when first discovered 10 Spreading centers on the World Map world tour 11 History of the South Atlantic opening of new oceans in general Outline of Current Lecture 1 History of spreading in South Atlantic North Atlantic Eastern Pacific Labrador Sea and Indian Ocean 2 Rates of spreading rate is distance time usually km my or cm yr a The edge of the continent is usually not sea level but the edge of thecontinental shelf 3 Pacific Plate also has chain of islands from hot spot Hawaii These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Connection between mantle plume hot spot island chain b Rate of motion calculation distance time usually km my or cm yr 4 Subduction zones in continental and oceanic settings 5 Plate tectonics is the most efficient way for the earth to lose heat that s the simple reason that plates move 6 Early idea was that conveyor belt convection drives plate but it has problems 7 Some people now believe that plates slide away from ridges and toward subduction zones 8 World Tour of subduction zones Current Lectu What did we learn today Plates move because PLATE TECTONICS is the most efficient way for the Earth to lose heat Some people think plates slide away from RIDGES and toward SUBDUCTION ZONES The youngest seafloor is located at the RIDGES The oldest seafloor is located at edges of the CONTINENTS OR OCEAN BASINS Spreading rates are determined by dividing DISTANCE by AGE and rates are in Km my or cm yr Plates move over HOT SPOTS and create a chain of volcanoes Plate is destroyed at SUBDUCTION ZONE Only OCEANIC plate subducts under either OCEANIC or CONTINENTAL plate
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