preEarth, I am somewhat confused as to why you are attacking a mechanism - convection currents - that are not now thought to play a major role in plate tectonics. Indeed some researchers would hold that the currents are a consequence of plate movement, not the cause. It doesn't give your argument much credibility if you chose to attack outmoded ideas.
Later you say this:
How easy is it to believe that, over the last 200 million years, 65% of entire surface of the Earth has fallen down holes and disappeared?
I find it very easy to believe. The area may be large, the volume is comparatively small. More to the point seismic data reveals subducting slabs. We can see the 'surface' disappearing.
I am further puzzled by your use of personal incredulity as an argument against plate tectonics. That's the second logical fallacy you've been guilty of - first a strawman and now this.
While we are on the subject of ocean floors, if plate tectonics does not occur how do you explain the presence of ancient ocean floor that has been obducted onto continents?
