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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
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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