Speed of Convection
See also: Heat transfer#Convection vs. conductionTypical mantle convection speed is 20 mm/yr near the crust but can vary quite a bit. The small scale convection in the upper mantle is much faster than the convection near the core. (See whole-mantle discussion above.) A single shallow convection cycle takes on the order of 50 Million Years, though deeper convection can be closer to 200 Million Years.
Read more about this topic: Mantle Convection
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