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EVIDENCE FOR PLATE TECTONICS

EVIDENCE FOR PLATE TECTONICS. Why Do Lithospheric Plates Move?. Heat Flow and Seafloor Elevations. Heat flow is a measure of the amount of heat leaving the rocks of the lithosphere.

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EVIDENCE FOR PLATE TECTONICS

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  1. EVIDENCE FOR PLATE TECTONICS Why Do Lithospheric Plates Move?

  2. Heat Flow and Seafloor Elevations • Heat flow is a measure of the amount of heat leaving the rocks of the lithosphere. • The values of heat flow are unusually high in the areas around spreading centers and decrease away from the centers. • This is exactly what should happen if spreading centers are places where hot convection currents are bringing magma to the surface forming new oceanic crust.

  3. Convergent Boundaries: Subduction • A subduction boundary is a form of converging boundary where one plate plunges beneath another overriding plate. • A characteristic feature of a subduction plate is a deep-sea trench. The deepest places on the ocean floor are in such trenches.

  4. Earth Science Reference Tables

  5. Why Do Lithospheric Plates Move? • Lithospheric plates rest upon the asthenosphere, which is a partially melted layer. • Convection currents within the asthenosphere are the driving force behind lithospheric plate movement. Within such currents, material expands and rises upon heating but contracts and sinks upon cooling. • Convection currents carry new material to the surface and pushes older material aside.

  6. Why Do Lithospheric Plates Move?

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