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Naturalists at Large: Plate tectonics
The document discusses plate tectonics, including that the Earth's crust is broken into plates that move atop the mantle. There are two types of plates - oceanic and continental. Plates interact at three types of boundaries: divergent boundaries where plates separate and new seafloor is created, convergent boundaries where plates collide resulting in subduction zones or mountain building, and transform boundaries where plates slide past one another causing earthquakes. Convection currents in the underlying mantle are cited as the cause of plate tectonic movement.
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Naturalists at Large: Plate tectonics
- 2. Theory of PlateTectonics Plate Tectonics Plate Boundaries Causes of Plate Tectonics
- 3.
- 4. What is PlateTectonics • The Earth’s crust and upper mantle are broken into sections called plates • Plates move around on top of the mantle like rafts
- 6. What is theLithosphere? • The crust and part of the upper mantle = lithosphere –100 km thick –Less dense than the material below it so it “floats”
- 7. What is theAsthenoshere? • The plastic layer below the lithosphere = asthenosphere • The plates of the lithosphere float on the asthenosphere
- 9. 2 Types ofPlates • Ocean plates - plates below the oceans • Continental plates - plates below the continents
- 10.
- 11. Divergent Boundaries • Boundarybetween two plates that are moving apart or rifting • RIFTING causes SEAFLOOR SPREADING
- 12. Features of Divergent Boundaries • Mid-ocean ridges • rift valleys • fissure volcanoes
- 16. Convergent Boundaries • Boundariesbetween two plates that are colliding • There are 3 types…
- 17. Type 1 • Oceanplate colliding with a less dense continental plate • Subduction Zone: where the less dense plate slides under the more dense plate • VOLCANOES occur at subduction zones
- 19. Andes Mountains, SouthAmerica
- 20. Type 2 • Oceanplate colliding with another ocean plate • The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH
- 22.
- 23. Type 3 • Acontinental plate colliding with another continental plate • Have Collision Zones: –a place where folded and thrust faulted mountains form.
- 26. Transform Fault Boundaries •Boundary between two plates that are sliding past each other • EARTHQUAKES along faults
- 28.
- 29. Causes of Plate Tectonics
- 30. Convection Currents • Hotmagma in the Earth moves toward the surface, cools, then sinks again. • Creates convection currents beneath the plates that cause the plates to move.