From: rsquires@cyclops.eece.unm.edu (Roger Squires)
Subject: Re: a challenge ignored?
Date: Tue, 28 Jul 92 00:10:16 GMT
Organization: University of New Mexico, Albuquerque


From macrae@pandora Sun Jul 26 09:06:35 1992
From: macrae@pandora.bio.ns.ca (R. Andrew MacRae)

	Well, plenty of time has passed since I posted this challenge  
for flood-creationists (July 15 or so), and I still have not received  
any responses:

>Hi:
>	In my original posting (a response to the "Grand Canyon
>Ichnofauna" thread) I kind of goofed.  One of the pieces
>of evidence I presented is easily challenged as evidence for
>land deposition: #6.  It isn't wrong in detail, but as I explained
>it, there are holes in the argument.
>	Rather than just post a correction, I challenge someone from  
>the flood-creationist camp to explain why #6 does not necessarily
>imply deposition on land (the way I have stated it).
>	Here is #6 again:
>	6) river channels - with distinctive point-bar cross-bedding,
>	and sinuous plan-view shape (i.e. meandering).
>
>If you find the answer, think of it as a demonstration of the
>careful scientific scrutiny given to all hypotheses by the
>flood-creation camp.  If you don't, well, I won't be impressed.
>It is easy.  (I feel so stuuuuupid).
>	I will wait one week before posting the answer.  Feel free to
>e-mail an answer to me.  I will summarize.
>	-Andrew
>	macrae@pandora.bio.ns.ca
	(After Sept.1: macrae@pandora.geo.ucalgary.ca)

	So, as promised, here is the answer.  I feel kind of stupid  
that I didn't think of this the first time:
	
	The reason the geometry of meandering river channels is not  
an exclusive indication of terrestrial deposition is that they _do_  
occur in the modern, submarine environment.  Their gross  
geometry/morphology is duplicated by gravity flow (turbidite)  
processes in deep-sea fans.  The best known example is the sediment  
cone off the continental shelf at the Amazon River [e.g., Damuth,  
J.E., et al., 1983.  Distributary channel meandering and bifurcation  
patterns on the Amazon deep-sea fan as revealed by long-range  
side-scan sonar (GLORIA). Geology, v.11, p.94-98].  The meandering  
channels occur to several thousand metres depth, and although similar  
in geometry (what I stated in #6), they differ in many of the  
associated sedimentary structures.
	
	I must say I am not impressed with the flood-creationists.  I  
did not receive a single comment or alternate hypothesis.  This was a  
chance for you guys to show your skills at testing hypotheses and  
"debunking" conventional geology.  Maybe I am not being fair saying  
this - because not enough people saw the post, or I missed a  
response, or maybe my e-mail address is hosed - but  
flood-creationists failed.  Maybe it has to do with the "modern  
analogue" answer, since flood-creationists seem so loathe to explain  
other geologic evidence with processes that are occurring now  
(because they claim to be uncomfortable with "uniformitarian  
assumptions").  Whatever the explanation, how do flood-creationists  
expect to replace conventional geologic explanations if they do not  
answer challenges like this?  Plenty of interested people in  
talk.origins answer creationist explanations with scientific  
alternatives.

	Anyway, the original statement I made is still truthful if  
you add other distinctions between river channels and channels in  
submarine fans: river channels are associated with other terrestrial  
evidence (e.g., floodplain deposits - land plants, paleosols,  
mudcracks, etc.), while submarine fan channels are associated with  
marine evidence (e.g., marine animals) and have evidence of  
gravity-flow deposition (i.e. turbidites - graded beds with Bouma  
sequences) associated with them.
	So hopefully flood-creationists will not attempt to use  
submarine fan channels as an explanation for river deposits...  
although it would not surprise me if they already have :-)
	
	-Andrew
	macrae@pandora.bio.ns.ca
	(After Sept.1: macrae@pandora.geo.ucalgary.ca)