Extinctions Too Complex for Simple Stories

Impact theories of extinction are fighting for their own survival.  A commentary in PNAS¹ warns that extinction theories are more complex than can be handled by a single event, like a meteor impact.  At best, they might be invoked as the coup-de-grace in a series of situations.  Hermann Pfefferkorn reveals the complexities in the Permian and Cretaceous extinctions, and says it is doubtful the extinctions can be tied to singular events.  “An impact could have increased the intensity of an ongoing major volcanic event,” he says.

¹Hermann Pfefferkorn, “The complexity of mass extinction,” Proceedings of the National Academy of Sciences USA, August 31, 2004, vol. 101, no. 35, 12779�12780.

Scientific advance is the art of poking holes in neat, easy stories: see “First Law of Scientific Progress” in right column, below.
    Interesting that Pfefferkorn, in his brief history of geological thought, redefines the old Lyell doctrine of uniformitarianism for the postmodern era.  Lyell would hardly recognize the new definition:

Today, uniformitarianism is defined as the constancy of physical and chemical laws over time, while the rates and areal extent of any given process can be variable.  In addition, there are processes that happen so rarely that humans have never observed them during the exceedingly short span of written history.  Thus, catastrophes are now part of our uniformitarian understanding of Earth processes.

Now, everybody wins, and everybody gets a prize.