Scientists hypothesized that the end of a certain geological period came about when a cataclysmic meteor impact near the equator caused debris to fly up into the atmosphere, where it was scattered by winds, blocking out the sunlight and abruptly killing off many species. In European rock layers, the fossil record of the boundary layer that marks the end of the period supports this picture of rapid, mass extinction of life. But the boundary layer in the Antarctic is much thicker
that it appears that the extinction process there lasted a much longer time, contrary to what the hypothesis would have predicted.
The rock layers in the Antarctic were examined many years after the rock layers in Europe.