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Re: K-T impact theory
At 10:59 PM 5/28/97 -0700, Jonathon Woolf <email@example.com> wrote, anent
the impact theory of the K-T extinction:
>I don't think you understand the full scope of my question. Nuees
>ardente wipe the ground clean. _Everything_ is gone. Trees get
>charcoaled on the spot. Brush is simply vaporized. Animals are broiled
>alive. Seeds are either killed by the heat or buried too deeply to
>germinate. Nothing larger than a gopher survived the Mount St. Helens
>ashblast, and those few animals that did survive the blast all died
>within a couple of years because of lack of food.
Actually, a great many animals larger than gophers survived the Mt. St.
Helens eruption; I am one of them. I was too far away from the blast to
have been killed by it.
>Are you seriously
>suggesting that life could recover from a disaster of far greater
>magnitude across all of North America in a few thousand years?
The proponents of the K-T impact theory do not suggest that the immediate
blast effects were instantaneous and worldwide. Far bigger than Mt. St.
Helens, certainly, but global primarily in secondary effects, such as
alterations in weather patterns reducing photosynthetic energy binding for a
period of time sufficient to bump off really big (in size and quantity)
consumers of food, as well as other organisms sensitive to such changes.
>An impact of the sort currently fantasized would eliminate
>_everything_, all macroscopic life. The record shows that not
>everything was eliminated.
Woolf claims that someone is "fantasizing" here, rather than assembling
available date in a legitimate attempt to solve a conundrum. Why use this
word, "fantasized," to characterize the honest searching of so many
honorable and dedicated workers, with such diverse and elegant resources at
their disposal? "Fantasy" is the realm, expertly navigated, of such as Mr.
Spielberg the movie-maker. He and his colleagues are not the source of the
K-T impact theory.
>An "asteroid winter" of the sort currently
>imagined would have killed every photosynthesizing cell on the planet,
>as well as forcing the temperature so low that endothermic mammals would
>rapidly die of starvation (look it up, no shrew can go a week without
>eating, and the asteroid scenario requires them to go years without
Not at all. The people espousing the K-T impact theory have assembled data
that suggest entirely otherwise. Yes, the impact of, say, a Moon-sized
object (the size, that is, of Earth's present natural Moon) might have the
effect that Woolf suggests, killing "every photosynthesizing cell on the
planet," but the object considered by those pursuing the K-T impact theory
is orders of magnitude smaller, a rock about seven miles in diameter.
>Plants can't grow without soil. Soil requires an
>organic component. A blast of the described magnitude should have
>eliminated every scrap of organic material in the direct blast region.
This happened on Krakatao. But life returned, and quickly, too, the operant
clause in Woolf's statement above being, of course, "the direct blast region."
>In short, the kind of impact
>blast currently being proposed should have put life back to a Cambrian
>or even Late Precambrian stage.
Not at all. The kind of impact blast currently being proposed is more or
less the sort that would produce the changes seen at the K-T boundary, if
the theory's proponents are correct. Whatever they're doing, however, these
people are not "fantasizing." They are working, and have produced a
skeletal hypothesis that, for the moment, seems to be growing some meat on
>The asteroid theory doesn't work. The effects it predicts don't appear
>in the record, and the effects that do appear in the record don't make
>any sense as the handiwork of an impact.
If, indeed, the effects that the impact theory predicts don't appear in the
record, it will soon enough be abandoned. In the meantime, many of the
planet's best researchers find that it is at least as good a hypothesis as
any other that has been presented to date. No one yet claims certainty, but
no one is merely fantasizing, either.
>So are we supposed to ignore the facts because a theory is too elegant
>and emotionally appealing?
Certainly not. Nor are we to discard an unfolding theory, and dub its
proponents "fantasizers," simply because we choose not to take the time to
understand its present iteration.
I speak, by the way, as one not entirely convinced of the veracity of the
impact theory. I am nonetheless totally convinced of the truthfulness and
scientific goodwill of those analyzing it (and other theories) in hopes of
coming to firmer ground in this issue.
John C. McLoughlin