I've been studying up something known as the Younger Dryas Impact theory (and a bunch of other descriptions), the Cliff Notes version is that I'm now convinced that about 12,800 years ago there was some sort of massive explosion(s), likely centered over North America, probably caused by asteroid(s) that caused a very quick melting of the ice sheets that covered much of the continent and created a flood of such epic proportions that it staggers the mind. Imagine walls of water and debris hundreds of feet high racing at several hundred miles an hour destroying everything in it's path. Much of the planet was affected, but not equally, and the effects of all this was a devastation that changed forever, human and animal population, the landscape, the earth's climate and the history of human culture. The scientific evidence that such an event occurred is substantial, but mainstream science seems slow to accept it. Most lay people have never even heard of it, but it is probably the most important event in the history of this planet.