I couldn't find a thread on this, and it is a very interesting piece worth seeing. It discusses the Permian mass extinction, as well as some other
related things. It also talks about the Siberian Traps, and a potential new theory that an even bigger asteroid than what "killed" the dinosaurs hit
during the Permian period. Because of the incredible force of such a massive impact, it is postulated that it melts the earth's crust and that the
crater refills with lava- leaving no crater at all.
They discover some things in the earth layers, after noting a 23,000 year cycle. There's tons of stuff in here, and it leads to new conclusions about
the epoch. That it may have actually been a combination of factors, and not just one.
Enjoy and learn!