Why are convection currents in the mantle? Explain?

Answer 1

Ever boil a pot of water? It is where the term "rolling" came from. This is the same as in the mantle. As heating occurs, it becomes less dense, rises to the surface, cools and sinks again, in essence a "rolling" or convection occurs

Answer 2

If there was substantially less radioactive material in the Earth's core, there wouldn't be any convection currents. The mantle would be hot at the bottom, but not molten, and the temperature difference from bottom to top would stabilise at the value which was just enough to carry away all the generated heat.

But there is more radioactivity than that, and the temperature builds up until the mantle softens and begins to convect as well as conduct. This increases the total heat transfer rate, until it equals the rate at which heat is being generated.

If there was even more radioactivity, the mantle would have to soften more, and convect faster, giving us faster continental drift as the crustal plates were dragged sideways on top of the various convection cells.

Answer 3

The Earth's core is the source of heat under the continental plates. As the magma nears the core it heats up. Because of this is moves up(away from the core)due to its heat. As it moves away from the core it looses heat until it sinks back down near the core again to be heated again, creating a wavelike motion known as convection currents.
That is just to my understanding...

Answer 4

I am not clear on the question, please elaborate what you wish to know.
Thanks,Ed