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Plate Tectonics and Continental Drift PowerPoint Presentation
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Plate Tectonics and Continental Drift

Plate Tectonics and Continental Drift

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Plate Tectonics and Continental Drift

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  1. Plate Tectonics and Continental Drift

  2. Plate Tectonics • The surface of the Earth is composed of about a dozen major rigid, moving crustal plates and several smaller plates • Plates • a. Slabs of Earth’s lithosphere (crust and upper mantle) • b. Average thickness is 100 km (62 miles) • c. Most plates support both continent and ocean

  3. Continental Drift states that the continents have drifted and still are drifting apart

  4. Why do the plates move? • Due to tremendous heat, rock in the asthenosphere is like hot taffy • This allows plates to ride on top of hot, flowing rock. • 3. Plates move because heat is being released from deep inside the earth. • 4. Convection currents causes hot material to rise and expand (plates diverge) and cooler material to sink and contract (plates converge).

  5. Continental Drift _________ proposed the theory that the crustal plates are moving over the mantle. This was supported by fossil and rock type evidence; also matching of coastline shapes. Wegener

  6. Convection Currents The force responsible for plate movement is __________.

  7. Plate Boundaries • The following two slides show maps of the current major plate boundaries and their relative motions. • You should be able to describe various landforms created by different plate movements.