[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: extinction



Dewey McLean (dmclean@vt.edu) wrote:

<In 1986, Olmez, Finnegan, and Zoller published a paper titled "Iridium
emissions from Kilauea volcano" (Journal of Geophysical Research, 1986). 
Following is a direct quotation from the paper:>

  The argument appears to favor a generalized, and undated or general
dated effusive magmatic dispersal of all the K/T indicators. The problem
is that none of the data argues conclusively that the Deccan Traps _would_
have done this, since the time period and relative effusive concentration
of elements traced around the world seems to indicate around 1 my worth of
generalized downpouring. The Deccan Traps themselves show intermittent
periods of effusion and dormacy, rather than a singular, mass, or steady,
event that led to the K/T boundary. Traces around the world tend not to
match to a single, or even three, events of lesser magnitude than that
looked for by the Chixulub advocates. Instead, some argue, the Deccan
Traps, beginning largely congruous with the "Shiva" site of Chatterjee's
favored impactor, were antipodal to the Chixulub impact, even if the date
is kind of off. This is not neccesary to be identically dated, as the
magmatic effects may easily have been instigated, but not eruptive, until
thousands of years after the impact weakened the antipodal crust. Again,
theory.

  There is a flaw always in the argument that a _single_ event caused the
K/T extinctions, rather than compounding, gradual events that were
worsened by various natural disasters, the least of which were local
Deccan effusions of basalt, and antipodally a giant impactor that woulkd
have devastated the local ecology and definately made what happened at
Krakatoa and elsewhen magnitudes worse events following. Do we need a
single event? Does this argument for simplicity neccessarily reflect
reality, or should it?

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

__________________________________
Do you Yahoo!?
Yahoo! Hotjobs: Enter the "Signing Bonus" Sweepstakes
http://hotjobs.sweepstakes.yahoo.com/signingbonus