GEOL 104 Dinosaurs: A Natural History

Fall Semester 2006
The Cretaceous-Tertiary Extinction III: Not With a Bang, But a Whimper

Media (and some professional scientists) act as if K-T impact was only global change occurring at K-T boundary.

However, equally good geological evidence for some other big changes:

Increased Volcanism:
Long known that a period of intense volcanism begins in later part of Cretaceous. In North America, associated with change in mountain building in Rockies. Biggest aspect of volcanism, however:
Deccan Traps

Some try to dismiss Deccan Traps as a side effect of Chicxulub crater, but begins a little too early.

So, Deccan Traps themsevles were a MAJOR event, and might have contributed greatly to the extinction event.

Even earlier geological change:
Maastrichtian Regression

Maastrichtian Regression clearly happens (latest Maastrichtian terrestrial rocks on top of earlier Maastrichtian shoreline rocks on top of earlier marine rocks).


All three events (Chicxulub impact, Deccan Traps volcanism, Maastrichtian Regression) are known to occur. Can we separate their effects in the geological record?

And which, if any, seems to have an effect on dinosaur diversity?

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Last modified: 14 July 2006