Is when hot parts of the earth rise as cooler parts sink

due to differences in density.

Yes

Explanation:

When cooler parts of air sinks, it causes high pressure

The hot parts rise as the sinking of cooler, denser material pushes the heated material up. This kind of movement of material due to differences in density is called convection.

Explanation:

At seduction zones, a denser tectonic plate sinks, or sub ducts, beneath another, less dense plate.