From: Darryl Maddox (dpmaddox@arn.net)
Date: Mon Mar 31 2003 - 07:52:58 EST
Hi all,
I remember learning about peneplains in the 1960's when I was in my first
couple of years of studying geology. At the time I wondered what kind of
env. would give such a phenomena, later, when I began to seriously look at
the Permian/Triassic boundary in Palo Duro Canyon in the Texas Panhandle I
again wondered what kind of env. would produce such a planer surface, and
now the question is again being discussed here. I can't answer for
everyone and I haven't seen the Grand Canyon but I have seen the Texas Gulf
Coast and I have seen pictures of the desert plains of Kuwait and Iraq and
am convinced that either will produce surfaces flat enough to be considered
peneplains when seen from the top or when their surface topography is
mapped, and/or essentially straight line paraconformities or
non-conformities - nonconformity in the case of PDC since there is a
lithological difference across the boundary but in many places it isn't much
more, if any more different that other boundaries within the Permian and
within the Triassic which are not considered unconformities.
Confirming or contrary thoughts or facts I should know about?
Darryl
----- Original Message -----
From: "Bill Payne" <bpayne15@juno.com>
To: <asa@calvin.edu>
Sent: Sunday, March 30, 2003 8:51 PM
Subject: Paraconformities (was test questions)
> On Fri, 28 Mar 2003 20:19:59 -0500 "bivalve"
> <bivalve@mail.davidson.alumlink.com> writes:
>
> > Plains and plateaus are my modern analogs.
>
> I have just completed 7 weeks of field work in the Great Plains of west
> Oklahoma, and those Plains are too irregular to form the flat (plane)
> strata we see in Grand Canyon and other locations of the West. We do see
> mesas (tabletop mountains) which, I agree, are very flat, but not very
> extensive, having been cut by erosional channels.
>
> > Sure, they usually have
> > river channels, but there is flat land between the channels that is
> > eroding relatively evenly. The odds that a particular outcrop will
> > have a channel running through it is less than 100 percent.
>
> This is the weakness of your proposed mechanism. The Grand Canyon is
> more than any "particular outcrop." The exposures there are tens of
> miles long, some of the gaps in deposition are supposedly millions of
> years, and yet the strata above and below the gaps are flat and
> continuous. The only two ways I can see to accomplish these results are
> by (A) sheet-flow erosion, or (B) nearly continuous deposition, i.e.,
> breaks in deposition of minutes, days or possibly years, but not millions
> of years.
>
> > Ordinary rainfall will do the job nicely.
>
> No, this will create channels and canyons - which we do see in the mesas,
> but do not see in many paraconformities.
>
> > However, this raises a
> > more basic question that needs answering before this discussion can
> > get anywhere. What is your flood model? You need to provide a
> > coherent model and to show that it fits the evidence as well or
> > better than conventional geologic explanations.
>
> There you go, David. Michael said these arguments can't stand up to
> scrunity. I have presented three arguments, two of which I yielded, but
> this third one you first said you weren't motivated to research and
> answer, now you have tried to respond and probably are beginning to see
> that your answers are strained by the data. So you try to shift the
> focus by jumping to the big picture. Michael tried to avoid this
> altogether with his curt reply and his claim to be "bored" with this
> argument. Both tactics, yours and Michael's, are common in these types
> of discussions, and indicative of a certain insecurity.
>
> > The fact that you
> > can find problems with any scientific theory does not automatically
> > mean that a particular alternative is better.
>
> No, but if I can offer better solutions to the problems than you can,
> then one begins to wonder. After all, isn't this how science is supposed
> to work?
>
> > Likewise, invoking
> > the Flood to do anything they want is a popular way for Flood
> > geologists to damage their scientific credibility.
>
> First, I haven't invoked the Flood to do anything I want, and second, as
> a PG, I am mildly offended (and also mildly amused) by your inference
> that I have damaged my scientific credibility. In response to Michael's
> challenge, I have attempted to offer empirically-based alternatives to
> conventional interpretations of geology. I have yielded on two counts,
> but in light of your and Michael's failure to provide reasonable support
> for your view of paraconformities I am standing firm on this one until I
> see a stronger defense.
>
> > For example, why
> > would the Flood produce sheet flow?
>
> You are asking the wrong question. You should be asking if sheet flow is
> the best explanation for the observations. You're letting your paradigm
> drive your conclusions, rather than following the science where it leads.
>
> > What layers were produced by
> > the Flood?
>
> Again, wrong question. You should be asking whether a Flood acting over
> a short period of time or rainfall acting over millions of years would
> best explain our observations of the paraconformities I have cited.
>
> Bill
>
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