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Difficulty: EasyEarth's Interior and Plate Tectonics

Tectonic plates float on the semi-fluid asthenosphere and move across Earth's surface over millions of years. What cyclical heat transfer mechanism within the mantle provides the primary driving force behind this plate motion?

  1. A
    Thermal radiation
  2. Mantle convectionAnswer
  3. C
    Crustal subduction
  4. D
    Magmatic crystallization

Answer

Mantle convection is the heat transfer mechanism responsible for driving plate motion.
Mantle convection is the continuous circulation of ductile rock within Earth's mantle caused by heat escaping from Earth's core. Warmer, less dense material rises toward the crust, cools near the lithosphere, and sinks back down as its density increases. These circular currents generate frictional forces that pull and propel the overlying tectonic plates across the surface.

Step-by-Step Solution

1
Identify the primary mechanism of heat transfer occurring in fluid or semi-fluid materials under temperature gradients.
Convection involves the cyclical movement of warmer, less dense material rising and cooler, denser material sinking.
Earth's internal heat creates substantial thermal gradients between the deep interior and the lithosphere.
2
Relate mantle convection currents to the mechanical movement of the overlying lithospheric plates.
As convection cells circulate through the asthenosphere, they exert lateral shear stress and gravitational pull on tectonic plates, causing them to move.
The plates of the lithosphere rest directly on top of the ductile mantle material.

Key Concept

Mantle convection as the thermal engine of plate tectonics
Estimated Time:45s
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Topics

Earth's Interior and Plate Tectonics

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