Caption: "This figure shows a computer simulation for thermal convection (i.e., mantle convection) in the Earth's crust (5--10 km oceanic crust; 30--50 km continental crust), average thinkness 2886 km, ∼ 84 % of the Earth's volume. Colors closer to red are hot areas and colors closer to blue are cold areas. In this figure, a hot, less-dense lower boundary layer sends plumes (mantle plumes?) of hot material upwards, and likewise, cold material from the top moves downwards." (Somewhat edited.)

Features:

1. The Earth's crust is probably negligible in this computer simulation and the ∼ 30000 km depth is probably the core-mantle boundary.

2. The horizontal axis is ∼ 8500 km or ∼ 1/5 of the Earth's equatorial circumference = 40075.017 km.

3. The turbulence of convection is manifested in the figure by the varying plumes, swirls, and eddies.

4. The core-mantle boundary is the source of the heat energy of the convection.

5. The convection cycle period for deeper convection is ∼ 200 Myr (see Wikipedia: Mantle convection: Speed of convection).