Permian-Triassic Mayhem: Earth's Largest Mass Extinction

This is an amazing talk, most of the Royal Tyrell lecture series talks are good, but this one stands out.

I'm not sure how much confirmation the theory this geologist expounds has, but it seems like a large volcanic episode burned up enormous coal deposits, running up the CO2 content of the atmosphere, causing rapid climate change. The coal and the vulcanism unleashed really large quantities of mercury, which is pretty toxic. Absolutely fascinating.