Comet Blast 13,000 Years Ago?

A new study argues a comet exploded over what is now central Mexico some 12,900 years ago. Evidence for such a blast include the presence of spherules and nanodiamonds in a thin layer at the site which could only have been created under extreme heat and pressure. Further, a similar layer dated to precisely that same time has been found at many places across at least the northern hemisphere, suggesting a worldwide event did in fact occur.

The timing of the alleged event also coincides, at least roughly, with the latest large extinction event in the fossil record, which saw the ending of the reign of the megafauna-- mammoths, giant bison, saber-toothed cats-- in North America. It also coincides with a change in the global climate which would be consistent with such a titanic explosion.

Of course, this new theory will be challenged, just as the theory that an asteroid impact sealed the fate of the dinosaurs is still being debated. Most scientists still favor explanations based in gradualism-- slow change over geologic time-- as opposed to catastrophism, which says change can be brought about by huge, specific events. Both approaches obviously operate in the real universe.