Re: Coconino sandstone

Ed Brayton (cynic@net-link.net)
Wed, 30 Sep 1998 11:41:25 -0400

Arthur V. Chadwick wrote:
>
> At 06:14 PM 9/29/98 -0400, you wrote:
> >Art-
> >
> >Your name recently came up, along with Elaine Kennedy, in a long
> >discussion on the Grand Canyon. I have seen the abstracts of the work
> >you and Elaine have done on the Tapeats sandstone, but I'm wondering
> >what your opinion is on the Coconino sandstone. Is it your position that
> >the Coconino is a subaqeous formation, and if so on what basis? Thanks.
>
> Leonard Brand has published a series of papers on the Coconino SS. In
> these papers, he establishes pretty definitively that the Coconino has to
> be water deposited based entirely on the vertebrate trackways there. I can
> get some references for you , and tehy are in the bibliography of his book.

I am familiar with Brand's work on the trackways, at least the one with
the salamanders. Has he done any work with the various ichnospecies
tracks? It seems to me that these tracks are a major problem for those
who argue that the strata of the GC were laid down in the flood
regardless of the immediate environment in which the tracks were laid
down. There are some 5000 feet or so of sediments below the Coconino
that are generally attributed to this flood. I have a difficult time
envisioning that the animals that left the tracks in the Coconino
somehow managed to dodge the sediments being deposited at around a foot
an hour, while also managing to breathe and find food in water saturated
with enough detritus to account for all of the strata, to be alive by
the time the Coconino was laid down. If there is a flood model that can
explain that, I've yet to see it. Also, my information is that there is
a large range of data beyond these tracks, from the slope of the cross
bedding to the frosted nature of the sand grains to horizontal wind
ripples and more - that is far more consistent with terrestrial
deposition than with subaqeous deposition. You say that Brand argues for
subaqueous deposition based entirely on the trackways. Does he deal with
the geological evidence for terrestrial deposition at all?

Thanks.

Ed