The mechanism rodin is looking for is simple plate tectonics. Yes, it is still a theory. But the *measurable* changes due to plate tectonics make it plain that it is the reason/cause of continental drift. not to mention Hawaii.

For the earth to *expand* there would have to a penalty-less increase in volume for which the absorbed hydrogen theory is just absurd. I can only picture such a thing causing a fusion-like reaction that would incinerate the earth.

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---"Why do things have to suck so bad?" a friend once asked me.
"Because space is a vacuum and that's a lot of suck." I replied.
(Actual quote)---