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Earth Systems Science Core
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Get a Move On!


What forces can be large enough to move these tectonic plates, enormous chunks of crust and rock, around Earth? What is strong enough to cause earthquakes, volcanic eruptions, mountain building, plateau formation, and all of the other continuously occurring geological processes?

Scientists are still not exactly sure, since the forces are unseen and unviewable, but we have a good guess. Our best idea is that the core of Earth is radioactive and continuously emitting heat, along with residual heat caused by gravitational energy left over from the formation of Earth.

This heat is causing convection currents which act much like a conveyor belt, causing the plates to move around on the semi-liquid material of the asthenosphere. Convection currents or convection cells are caused when heated material becomes less dense and rises up through the mantle. This material then cools, condenses, and sinks back towards the core, where it is reheated and the process cycles. You have probably observed this action if you have watched water boil or a pot of thick soup simmer on the stove. This process within Earth is MUCH slower, but it operates in a similar way.
How many convection cells are there within Earth? Where and how did they originate? What is their structure? How and why this energy coming from the core to the surface concentrates into these cells remains a mystery. Because these forces are buried so deep, we cannot test and prove any idea beyond a reasonable doubt. It is a good thing that we do not have to understand the motion for this action to occur!
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Updated October 24, 2008 by: Glen Westbroek

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