Continental Drift and Plate TectonicsTake-Away PointsGlobal Problems in GeologyDevelopment of Continental DriftThe Permian Ice Age ProblemWegener’s TheoryDating the BreakupFrank TaylorSlide 9Confirmation of Continental DriftThe Geomagnetic Reversal Time ScaleDiscovery of Sea-Floor SpreadingSea-Floor SpreadingWhere Does Ocean Crust Go?Benioff’s InterpretationBenioff’s Interpretation UpdatedWorldwide Standardized Seismic NetworkThe Plate Tectonics ModelSlide 19The Earth’s PlatesGlobal Plate MotionsWhat Drives It: ConvectionHow Plates MoveReconstructing Plate MovementsFit of Continents Across the AtlanticPresent Day AtlanticAtlantic 65 m.y. agoGeology of Plate MarginsOphiolites: Oceanic CrustAnatomy of a Mid-Ocean RidgeFAMOUS: Close-Up of the Mid-Atlantic RidgeMagnetic Stripes in the FAMOUS AreaA Subduction ZoneWhy Mountains are HighWhere the Plates MeetTerrane AccretionTerranes in Western North AmericaPlate Boundaries and EarthquakesHot SpotsHot Spots: HawaiiPacific Hot Spot TracksContinental Drift and Plate TectonicsTake-Away Points1. How we know plate tectonics happens2. Most earthquakes and volcanoes occur along plate boundaries3. New ocean crust is created along mid-ocean ridges4. Old ocean crust is recycled at subduction zones5. Subduction zones are where mountain-building (orogeny) occurs6. Small pieces of crust (terranes) are important in building up continents7. Hot spots are long lived stationary magma sourcesGlobal Problems in GeologyDistribution of Continents Mid-ocean Ridges Trenches Orogenic Belts•Deformation •Metamorphism •Volcanism •EarthquakesDevelopment of Continental Drift•Lots of people had noticed that the coastlines of Africa and South America are similar•Frank Taylor (1910) •Alfred Wegener (1912) Die Entstehung Der Kontinente Und Ozeane 1. How we know plate tectonics happensThe Permian Ice Age Problem1. How we know plate tectonics happensWegener’s Theory1. How we know plate tectonics happensDating the Breakup1. How we know plate tectonics happensFrank Taylor•In some respects, Taylor’s ideas were more modern than Wegener’s•Taylor always thought Wegener had stolen credit from him1. How we know plate tectonics happensFrank Taylor•Recognized role of Mid-Atlantic Ridge•Never reconstructed the continents like Wegener did1. How we know plate tectonics happensConfirmation of Continental Drift•World War II technology• International Geophysical Year (IGY) 1957-58 •Worldwide Standardized Seismic Network 1963- 1. How we know plate tectonics happensThe Geomagnetic Reversal Time Scale1. How we know plate tectonics happensDiscovery of Sea-Floor Spreading 1. How we know plate tectonics happensSea-Floor Spreading1. How we know plate tectonics happensWhere Does Ocean Crust Go? Hugo Benioff, 19541. How we know plate tectonics happensBenioff’s Interpretation1. How we know plate tectonics happensBenioff’s Interpretation Updated1. How we know plate tectonics happensWorldwide Standardized Seismic Network2. Most earthquakes and volcanoes occur along plate boundariesThe Plate Tectonics ModelThe Plate Tectonics ModelThe Earth’s PlatesGlobal Plate MotionsWhat Drives It: ConvectionHow Plates MoveReconstructing Plate MovementsFit of Continents Across the AtlanticPresent Day AtlanticAtlantic 65 m.y. agoGeology of Plate MarginsOphiolites: Oceanic CrustAnatomy of a Mid-Ocean RidgeFAMOUS: Close-Up of the Mid-Atlantic RidgeMagnetic Stripes in the FAMOUS AreaA Subduction ZoneWhy Mountains are HighWhere the Plates MeetTerrane AccretionTerranes in Western North AmericaPlate Boundaries and EarthquakesHot SpotsHot Spots: HawaiiPacific Hot Spot