The purpose of Appendix V is to
summarize the most significant impacts and extinctions of the past 250 million
years. Not all really big impacts have led to major extinctions.
Not all really big impacts have led to
major extinctions. However, all major extinctions were caused by the initial
effects of a really big impact and its antipodal effects
In one way or another, really big
impacts did cause all of the major extinctions of the past 250 million years.
The major extinctions prior to the Permian are too obscure to figure out.
When we look at big and really big
impact and their results, there are two exceptions to the usual rule.
The usual rule is that a big impact
will create a hotspot at the antipode that will move in the direction of the
directional force imparted by the impact. A really big impact will not only
create a hotspot, but will also uplift a continent and cause a major
The first exception to the rule is the
impact at Manicouagan 214 MYA. The impact was large enough (barely) to uplift
the Western Antarctica continent. However, this event did not create a major
extinction. It did create a minor extinction, but it did not cause enough
damage to create a major extinction.
The second exception to the rule is the
huge deep ocean impact 132 MYA that uplifted the South American continent. This
impact and its huge lava outflow at Parana and Etendeka caused the Valanginian
Weissert Ocean Anoxic Event, but not an official major extinction.
An analysis of these two exceptions
shows that, even though they didn't follow the rule, they came very close to
following the rule. The other big and really big impacts did follow the rule.
A summary of all of the big and really
big impacts that are covered in this book is shown below.