Since this is not in the science side (and perhaps that was a mistake in the first place -- in fact now that it is discussing geology I'm moving it) the only recourse to someone who can't present real evidence or logic is to ignore them.
My suggestion in this kind of case is to simply register a post saying something like "I disagree but it is a science discussion that would be required to state why and that doesn't belong here."
Since so many have a challenge with that moving this to geology might make it easier.