i know perfectly well what convection is, far more than you seem to. especially as i have to deal with it on a day to day basis in my job.
the mantle circulates, there are plumes and sinks. not only are these predicted, but they have been mesured.
so the mantle is moving, as it's moving, it exherts drag. (is it just me or is there a bit of deja vu around here)
just because there are different layers doesn't mean that there isn't any movement.
espetially as the crust is a solid.(hmm, more deja vu)
give it up gm, you're talking crap and you know it. nobody can be this dumb.