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Plate Tectonics Geophysical Science

Plate Tectonics Geophysical Science. Introduction. Earth consists of layers Solid Inner Core Liquid Outer Core Liquid Mantle Solid Crust Crust floats on the liquid mantle. Introduction. Convection currents within the mantle move the “plates” of crust found on the surface

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Plate Tectonics Geophysical Science

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  1. Plate TectonicsGeophysical Science

  2. Introduction • Earth consists of layers • Solid Inner Core • Liquid Outer Core • Liquid Mantle • Solid Crust • Crust floats on the liquid mantle

  3. Introduction • Convection currents within the mantle move the “plates” of crust found on the surface • This movement creates: • Earthquakes • Volcanoes • Mountains • Ocean floor

  4. Plate Tectonics • Tectonic plates: Sections of the Earth’s lithosphere that fit together on the surface of the Earth like a jigsaw puzzle • Plate Tectonics: the study of how and why tectonic plates move and the results of their movement

  5. Facts about Plate Tectonics • “tectonic” comes from the Greek word meaning “to build” • Tectonic forces = forcespushing and pulling on the lithosphere are caused by convection currents in the mantle • Change the earth’s surface by moving the plates

  6. Facts about Plate TEctonics • The plates can move 2-15cm each year • The plates are pushed together or pulled apart causing areas to • build up (mountains) • separate (sea-floor)

  7. Continental Drift • Continental Drift = the theory that the continents were once part of one big landmass called Pangaea, but have moved apart over time • Developed by Alfred Wegener in 1915

  8. Evidence for Continental Drift • Evidence for continental drift: • Paleontologists (scientists who study fossils) found identical fossils on two or more continents, despite their separation by oceans • Similar glacial deposits were found on four separate continents

  9. Evidence for Continental Drift • Continue to monitor the changing earth through use of improved sonar equipment and satellites.

  10. Plate Boundaries • Divergent Plate Boundaries= the plates move apart • Spreading of plates causes lava to rise and form new oceanic crust • The areas where this occurs are called mid-ocean ridges • Mid Atlantic Ridge • East Pacific Rise

  11. Plate Boundaries • Convergent Plate Boundaries= plates move towards each other • The plates push into each other • Because oceanic crust is denser than continental crust, it will sink under the continental crust at what is called a subduction zone • The oceanic crust sinks back down into Earth’s mantle where the crust is then re-melted • Where rocks of similar density collide they form mountains

  12. Plate Boundaries • Transform Plate Boundaries: 2 plates slide past one another • Example San Andres Fault • Often sources of Earthquakes

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