Ah I do love the way a thread can drift. Tho not so sure it's continental plates, seems too fast for that... they drift about as fast as our finger nails grow (about 2 meters in an average human life time).
I just can't think of a better analogy tho... as fast as a tree grows... as slow as a glacier... as fast as spring moving north (about 1/3rd of a mile an hour...)
Sorry I digress, where were we?
J