plate tectonics. 6-1 continental drift  continental drift  theory that the continents were...

Download Plate Tectonics. 6-1 Continental Drift  Continental Drift  theory that the continents were once a single land mass that broke apart  Pangaea  supercontinent

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  • Plate Tectonics

  • 6-1 Continental DriftContinental Drift theory that the continents were once a single land mass that broke apartPangaea supercontinent

  • Evidence of Continental DriftSouth America & Africa look like they fit togetherFossils of mesosaurus found in S. America & Africa

  • Evidence of Continental Drift cont.

  • 6-2 Seafloor Spreading 2 types of crustContinentalLess denseOceanicMore dense

  • 6-2 cont.Mid-ocean ridge underwater mt. chain in the oceansRift crackRift valley flat area btw. ridges

  • 6-2 cont.New seafloor magma rises up through a riftMagma cools making new crustNew crust pushes floor apart at ridges

  • 6-3 Evidence of Seafloor SpreadingTrench deep canyons in the ocean floor Most in the Pacific OceanOld crust ends up in trenches Melts & becomes magma again

  • 6-3 cont.Subduction zone area where crust is forced down in trenchesYoungest fossils = closest to rift valleys, ridges, & trenches

  • 6-4 Plate TectonicsTectonic plates the lithosphere broken into pieces7 major plates & 8 minor platesAsthenosphere liquid part of the mantle

  • 6-4 cont.Theory of Plate Tectonics explains how & why plates (continents) moveLithosphere floats on asthenosphere

  • 6-5 Plate TectonicsConvection current less dense warm rises & denser cool sinks3 types of plate boundariesConvergentDivergentTransform

  • 6-5 cont.Transform 2 plates sliding past each other Cause earthquakes

  • 6-5 cont.Convergent 2 plates move toward each otherOceanic + continental = oceanic subducts under the continentalContinental + continental = mountain

  • 6-5 cont.Divergent 2 plates move away from each otherCause rift valleysCause seafloor spreading

  • 6-6 Effects of Plate TectonicsEarthquakes plates slide past each other at a faultMountains plates collide & buckle upward

  • 6-6 cont.Volcanoes oceanic plate dips down & magma collectsHot spots place where magma reaches the surfaceIslands plates move over hot spots & volcanoes build