text:  theory on it, the effect that the tidal forces have, we do have to correct for the tidal forces in our gravity meters, because gravity is not a constant. But that's just one little piece of evidence that adds to your theory. My main questions are this. San Andreas tectonics have occurred really for the last 29, 30 million years, based on the evidence. Throughout the world, of course, it's a multi-billion year old cycle.