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well before the K-T boundary but lived right up to it. (And some
claim they lived on into the Tertiary!)
• Since three Deccan trap flows lie below the layer that contains
dinosaur remains, the dinosaurs, and presumably the other species
that were exterminated in the K-T event, survived at least the first
few phases of Deccan volcanism. Thus the eruption of the Deccan
volcanoes was not immediately inimical to life, even when the
volcanoes were right next door.
• Some geologists have speculated that a major meteorite impact
might have released so much energy that the earth's mantle below
ground zero melted, initiating a period of volcanism. In this view,
impact might have precipitated Deccan volcanism. But that idea
does not work for the Deccan eruptions, which began at least a
million years too early.
• Since the K-T boundary is located near the middle of
sedimentary layer ITIII, which itself was deposited well after the
volcanism that produced basalt flow III had ceased, it is hard to
understand how Deccan volcanism could have been the source of
the K-T iridium—the iridium was deposited after the Deccan
volcanoes had stopped erupting (though they did resume).
• Since none of the other intertrappeans have high iridium, the
element apparently was not produced in the normal course of
Deccan volcanism and intertrappean sedimentation. Its presence in
one thin layer among many suggests, if it does not demand, that
the iridium has a special origin, unconnected with Deccan basalts
and sediments. The extremely low concentrations of iridium in the
Deccan basalts—among the lowest levels ever measured—make
them a most unlikely source.
C AREER
D AMAGE
By the mid-1980s, not only did the volcanic theory appear to be los-
ing out to the Alvarez theory, some of its proponents felt that they
had been treated unfairly by the media. In 1993, Dewey McLean,
who has done as much as anyone to develop the volcanic alternative,
sent Science a complaint that the magazine had shown "indefensible
favoritism toward the asteroid and virtual censorship of the volcano
extinction theory. Since 1980, Science has published 45 proimpact
manuscripts and Research News articles and four strictly nonimpact
items." 1 4 Dan Koshland, editor of Science, responded that "For our
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