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Re: [Re: K-T question]



At 01:06 PM 6/2/00 -0600, Caleb wrote:
   Well, what I want to know is the paleopopulation with the plantlife as
immediately before and after (and during) the K-T boundary. Could you also
explain the warming-cooling trends in the plant life too, and when exactly
they occur?
There is some indication that this may be regionally specific.

In the Lance and Hell Creek there appears to be a narrow zone of depauperate flora immediately above the Iridium spike. This shows up mostly in pollen and spores, which become dominated by fern spores for a few centimeters above the boundary.

Further up the flora is decidedly cooler and wetter in aspect than that of the Latest Cretaceous. But that is to be expected, as world temperature reached a major low point during the earliest Paleocene. One correlate of this is that the formations overlying the Lance and Hell Creek have much more coal (lignite) than the earlier formations. Lithologically, the Lance and Hell Creek Formations end at the first regionally persistent coal bed. This is usually several meter above the Iridium layer.

However, there are strong indications that these results do NOT apply elsewhere in the world. In several sequences there is little detectable change in the flora across the boundary.


[Note, given the location and direction of the impact, central North America would have been particularly hard hit by the shock-wave and "fallout"].


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May the peace of God be with you.         sarima@ix.netcom.com