1 Class 1: Plate Tectonics Review!Today’s topics:! Earth’s compositional layers! Plate tectonics: theory & actions !Earth’s Compositional Layers!Atmosphere & Hydrosphere!Crust!Mantle!Core!Earth’s Atmosphere & Hydrosphere!2 Earth’s Crust!more dense!relatively light!CRUST!Earth’s Mantle!MANTLE!more dense!than crust!CRUST!Earth’s Core!highest!density!CRUST!MANTLE!CORE!3 Earth’s Magnetic Field rocky core Earth Requirements for magnetic field: 1. rotation 2. heat flow, convecting fluid 3. a mobile conductor (iron or metallic hydrogen) Global Earthquake Locations!Global Volcano Locations!4 Linking Observations!Continental Drift!Continental Drift (movie)!5 Ages of the Ocean Floor!Ma = Million years ago!1 billion years = 1 Gyr!1 million years = 1 Myr!1 thousand years = 1 kyr!Heat Flow!Warm colors = higher heat flow!Cool colors = lower heat flow!high at!ocean ridges!Global Topography and Bathymetry!ocean!ridges!6 The Puzzle Solved…..!earthquake locations!volcano locations!sea floor age!sea floor bathymetry!+ heat flow too!!Earth’s Tectonic Plates!Earth’s Tectonic Plates (movie)!7 Lithosphere & Asthenosphere!Plate Boundaries!Divergent Plate Boundaries!8 Seafloor Spreading (movie)!Convergent Plate Boundaries!1!2!3!Seafloor Subduction (movie)!9 Transform Plate Boundary!strike-slip!faulting!Transform Faulting (movie)!Plate Boundaries!Hotspots!10 Hot Spots!hot spot trail!Hot (not molten) rising plume!lithosphere!Formation of Island Chains!V1!V1!melting at base! of crust!V1!Formation of Island Chains (movie)!11 Example: The Hawaiian Chain!Fixed!hot spot!• Earth’s crust is divided into plates!• Plates move relative to one another at 1-15 cm/yr!• Plate interiors are largely undisturbed!• Deformation is concentrated at plate boundaries!Consequences:!• Plate tectonics constantly change Earth’s surface!• Earthquakes occur mostly at plate boundaries!• Volcanoes occur mostly at plate boundaries!Basic Premise of Plate Tectonics!1. Examine volcanic rocks !! Q: what was the source for magma?!How do we explore Earth’s interior?!2. Observe seismic waves from earthquakes! Q: where are the layers, what are their densities?!3. Examine meteorites! Q: what are they made of? like the core? !4. Existence and behavior of geomagnetic field! Q: what is the core doing?!12 • Satellites! ! ! 1 (Moon)! !!!• Size (radius)! ! ! 6378 km! !• Bulk density! ! ! 5.5 g/cm3 (4.1 g/cm3uncompressed)!• Surface gravity ! ! 9.8 m/s2!• Tectonism, volcanism!! yes (today)! ! !• Rotation ! ! ! 1 day!• Orbit!! ! ! 365.25 days!• Atmosphere !! ! 78% N2, 21% O2!• Surface pressure! ! 1 atm!• Surface temperature! 20°C (diurnal, seasonal changes)!• Plate tectonics! ! yes!• Water! ! !