... The theory used to be that convection currents in the upper mantel was what caused the plates to move, but I read somewhere that that theory has fallen out of favor as of late because of the lack of evidence that there actually are such currents. ...
Well I guess I'm out of date as well. I would not be surprised to see tidal effects and I would have expected that there would be currents as there are in the ocean. Hmmm.