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To John Alroy, et al.:
Sorry I was away for a few days while discussion brewed. Let
me preface this by noting that my original entry into this
imbroglio was directed to the statements by (Dr?) Alroy to the
effect that anyone arguing against a K/T impact-driven model is
sucking wind. I have no real opinion pro- or con on on the
matter, except that I know damned well that there is substantial,
professional controversy on the validity of the impact model. It
isn't a done deal.
To a few selected points in Alroy's recent missives (where do you
people find the time for all this discussion?):
>>>>"I agree that in principle alternatives to the impact model
for the mass extinction could be developed. In practice, I'm not
aware of a well-articulated, published development of such
There are many dozens of such articles, and you have discussed
them in your arguments (e.g. by Keller, Archibald, Williams,
Officer, Hallam, etc.). The problem is that you clearly will
dismiss contrary arguments as
"not well articulated."
>>>>"The Keller/Officer/etc. camp are trying to show that there
was no mass extinction, not that some alternate model can explain
No, they are basically arguing that the mass extinctions were
gradual and stepwise among various taxa. We all accept that mass
extinction occurs frequently in the fossil record. This also
supports the above statement by me.
>>>>"... the event most likely to be energetic enough to lay down
the sand bed beneath several hundred meters of water, concluded
the sedimentologists, seems to be an impact-induced tsunami."<<<<
How can anyone determine whether a tsunami is impact- or
seismically-driven? I'd like to meet the sedimentologist who can
postdict such an event with certainty. I believe you are taking
a S.W.A.G. as data.
>>>>" Of course there could be some who argue in a positive way
for an alternative, volcanism-driven model - again, where are the
They are numerous, and I fear this reveals that you are reading
Here is a sample:
J.-J. Jaeger, et al. 1989, Geology, v. 17, p. 316-319.
V. Courtillo, 1990, Scientific American, (October), p. 85-92.
N. Carter, et al. 1986. Geology, v. 14, p. 380-383.
A. Hallam, 1987, Science, v. 238, p. 1237-1242.
D. McLean, 1993, (Letter), Science, v. 259, p. 877.
McLean's letter is a good starting place because he specifically
discussed the bandwagon effect toward impact hypotheses and
>>>>"I'm amazed that the "2-3 m" issue won't go away. Why are you
so willing to ignore sampling effects and variation in data?
Furthermore, what is the EVIDENCE for this "gap"?<<<<
Very simple, its evident empirically in the field. Try doing
some "alpha" field work yourself and you may see the phenomenon
>>>>"Even if there WAS real, statistically meaningful evidence
for this "gap," it would show nothing apart from the existence of
variation in taphonomic regimes, which no serious paleontologist
In other words, you're so sure of your opinions that even
contrary evidence must be spurious. Seems to me some
creationists use the same logic. As for variations in taphonomic
regimes: there are sufficiently large sampled areas in the Hell
Creek/Lance/Tornillo Formations to discredit that argument.
Taphonomic effects should not be simultaneously pervasive across
Montana, Wyoming, and West Texas.
>>>>I'm sorry, but I'm getting frustrated with comments like
"Williams results are... pretty convincing... The existence of a
*large* drop in abundance of dinosaur bones (and teeth) in the
last few meters of the Hell Creek Formation is now a thoroughly
established fact." THERE ARE NO DATA IN WILLIAMS.<<<<
True, but I believe Mike Williams has spent a lot of time in the
Hell Creek outcrop and has seen the evidence first hand. Have
>>>>"Rogers et al. (1993: Can J Earth Sci 30,1066) compute an
average rate of sedimentation for the Two Medicine Formation of
7.0 cm per THOUSAND years. The supposed 2-3 gap would translate,
therefore, to no more than 43,000 years...<<<<
You might look at D. Ager's classic book "The Nature of the
Stratigraphical Record" (I believe the 3rd. ed. is 1992, Wiley &
Sons) which nicely argues that such models correlating duration
and sedimentation are useless. Ager is widely respected and most
sedimentologists I meet laugh at attempts to correlate rates of
accumulation of sediment with time.
>>>>... Sorry, I'm really getting steamed at this point... As I
said, there simply ARE no other craters on the scale of
Chicxulub. I am not going to argue particulars about the evidence
for Chicxulub being an impact crater because I feel that this has
been dealt with quite adequately by bona fide geologists...."
I am a geologist, and I find the matter has not yet been
adequately dealt with. Sorry you're getting steamed; rational
discourse should not anger you. I am astounded that you have such
childlike faith in and such vehement support for the opinions of
people concerning the verification of the Chicxulub structure as
impact generated, given that you admit you can't personally
analyze the evidence.
>>>>"Sociological claim: the anti-impact school does seem to be
losing out. Any new theory goes through phases of development,
and here is one way to outline the process:
a) Everyone believes in theory X.
b) Somebody proposes competing theory Y. This is either ignored
e) Proponents of X either give up (flat-earthers) or refuse to
give up but become completely marginalized in scientific circles
Substitute "cold fusion" for "flat-earthers" as your theory Y and
your argument falls flat. Or, substitute "mitochondrial Eve" or
"Nemesis" (your mentor Raup's idea). Lots of new hypotheses are
spurious, as are old ones.
>>>>"Participants in the conference went together to
examine a "tsunami" deposit and came away agreeing that a very
high-energy mechanism was needed to create it....<<<<
Tsunamis occur several times per year in modern times. What's the
big deal about identifying a tsunami deposit?
>>>>"New evidence has come to light of intact latest Cretaceous
sediments *inside* the supposed impact structure." .....I posted
on this before. The single published paper on this supposed
evidence (Meyerhoff, in Geology) provides no documentation for
the age of the "fossils" mentioned and is based on a log kept
during the drilling of the core more than 25 years ago. The
authors seem unaware of the possibility of reworking or
Meyerhoff and collegues have several decades more experience than
you in field studies on drill cores, and their in-house expertise
on identifying microfossils is hard to dispute. The age of the
data is irrelevant: facts don't age if they are valid. If the
log is preserved it is valid data. I still use old field notes.
How about you?
There is also a major component of the K/T boundary that seems to
be getting glossed here. That relates to the *factual* major
marine regression at boundary time. This, aside from the Deccan
Traps volcanics and the presence of a circular structure off
Yucatan, is one of the few facts in the subject. This latest-K
marine regression is not a trivial matter and seems to me the
best explanation for the decline of most marine taxa, such as
sauropterygians, mosasaurs, ammonites, etc. It also best
explains disappearances of paralic taxa such as pterosaurs and
many dinosaurs which are typically found in nearshore deposits.
Finally, I don't exactly know what a "flame war" is in your
sense, but controversy and discussion *are* the essence of
science. The aggressive responses to your postings may reflect
responses to notions in your initial (and subsequent) discourse
on whether or not various arguments are worth even making. Most
of us believe argument is critical and that orthodoxy is bad
science. I also believe other readers of this network will be
interested in knowing that the acceptance of the K/T impact
scenario is far from universal among workers.
David Schwimmer, Columbus College