What is Convection?

How do conduction and convection differ and what roles do they play in plate tectonics?

• How do conduction and convection differ and what roles do they play in plate tectonics?

• Answer:

  Conduction is the transfer of heat directly from one material to another with no movement involved. The heat from the core is conductively transferred to the lowest part of the mantle. Convection is the transfer of heat by movement of the hot material upward due to its buoyancy: The heat at the base of the mantle is carried upward by convection within the mantle - mantle material, whilst mostly solid can flow in a ductile manner. The heat is carried toward the surface by rising mantle material, and this can be erupted at ridges to form new oceanic crust. Convection or uprising of mantle material is also the cause of oceanic hotspots like Hawaii. Conversely, as the oceanic crust cools is becomes less buoyand and will ultimately become denser than the underlying mantle, which will cause it to sink back into the mantle, completing the convection cell.