In the case of the Younger Dryas, the jeopardy that humanity faced was not from nuclear missiles but from the incoming fragments of a disintegrating … - Graham Hancock

We might feel very sure that there is no more to reality that the material world in which we live, but we cannot prove that this is the case. Theoretically there could be other realms, other dimensions, as all religious traditions and quantum physics alike maintain. Theoretically, the brain could be as much a receiver as a generator of consciousness and thus might be fine-tuned in altered states to pick up wavelengths that are normally not accessible to us.

the evidence suggested that the Incas had often functioned as the restorers of these structures rather than their original builders.

An Ojibwa tradition seems relevant. It speaks of a comet that 'burned up the earth' in the remote past and that is destined to return:
'The star with the long, wide tail is going to destroy the world some day when it comes low again. That's the comet called Long-Tailed Heavenly Climbing Star. It came down here once, thousands of years ago. Just like the sun. It had radiation and burning heat in its tail ...
Indian people were here before that happened, living on the earth. But things were wrong with nature on the earth, and a lot of people had abandoned the spiritual path. The Holy Spirit warned them a long time before the comet came. Medicine men told everyone to prepare. ... The comet burnt everything to the ground. There wasn't a thing left ...
There is a prophecy that the comet will destroy the earth again. But it's a restoration. The greatest blessing this island [Turtle Island/America] will ever have. People don't listen to their spiritual guidance today. There will be signs in the sun, moon and stars when the comet comes down again.