[Repeal The 17th]

People have a tendency to imagine the tectonic plates
as being two-dimensional, but they are obviously 3-dimensional
and the exact depth and deep boundaries and pretty much unknown.

[Steve Van Doorn]

"(tectonic plates) are obviously 3-dimensional and the exact depth and deep boundaries and pretty much unknown"

My question is do they float on the magma? What keeps them from surging relative to the magma? Think of India and how it moved from South Africa to where it is.