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Re: craters and the k/t (Norm King)
I'm back from touring through the USA and Canada looking at dinosuar sites
and geological features. Excellent fun and it looks like I will be taking
this tour regularly in the future. However, this is not why I am writing to
I came back to 335 Email messages which I am slowly wadeing through and I
came across the on-going Craters and K/T extinction debate. While
State-side I picked up a book "The Great Dinosaur Extinction Controversey"
by Officer and Page (Helix Books, Addison-Wesley Publishing, Reading
Massachusetts) which has severely shaken my long-held beliefs in the impact
scenario for the K/T extinction. Their evidence is compelling and I urge
all parties interested in the issue to read this book.
Among their lines of evidence includes:
Irridium anomolies explained by volcanic eruptions;
Well documented faunal depletions prior to the K/T boundary across many
different groups of organisms;
A close and critical examination of shocked quartz;
Even the Chixalub crater comes in for a caning. According to Officer and
Page, no melt sheet has been found and (most compelling to me), there is a
relatively continuous sediment record in the crater through the late
Cretaceous and into the Tertiary. If this is a crater (Officer and Page
think otherwise) it should be couple of kilometres deep (according to the
calculations of Alvarez et al.) which means that most of the late
Cretaceous sediments should have been obliterated from inside the "crater"
Having been an ardent bolidist for some years now, this all came to me as a
confusing shock. I am still not 100% convinced by their arguments but I am
compelled to go back to the original publications and think the whole
subject through again.
I would be interested in hearing from other members of the list who have
read the book. Are bolide extinctions extinct?
Dr Paul M.A. Willis
Consulting Vertebrate Palaeontologist
Quinkana Pty Ltd