As far as Atlantis goes. I simply can't find anything about the myth that is totally unbelievable or that absolutely defies the laws of physics. Two conditions that are needed for dismissing it. Krakatoa was an island that was blown to smithereens in recorded history. There's a mile wide meteor crater in Arizona that took place in about the last 5k years of so. There was the explosion of a comet/meteor in Siberia in 1908. As I write a big hunk of La Jolla which is just a few miles from me went sliding down the hillside. Earthquakes, Volcanoes regulary tear up and destroy much of what man builds. Mankind regularly get clobbered by nature as such I don't see any reason why a similar event could have happened in ancient times to some forgotten civilization, of which the sole evidence is the "Atlantis" myth.