[snip]
>
>> If this material was deposited rapidly how is it that no unlucky, stupid,
>>or already dead animals managed to get buried in it? IOW why *only* trace
>>fossils in the Coconino?
>>
>That is a big question, whether it was deposited rapidly or slowly,
>subaerially or underwater.
>
Actually it's not so big. Deserts are notoriously poor in fossils because
the conditions do not allow for the long-term preservation of animal
remains. Few remains are buried deeply or long enough to give petrification
time to work, and there are few mechanisms by which petrification can
proceed.
>
>> All these things, reptile/mammal-like reptile tracks, spider & scorpion
>>tracks, the lack of body fossils, a sandstone made up of well sorted,
>>rounded quartz sand is perfectly consistent with a desert eolian sand dune
>>environment.
>>
>You believe that? I saw a diorama of that at a Grand Canyon visitor
>center, back in the 60's. That was before they knew very much about large
>submarine sand dunes, and ambulatory behavior of amphibians underwater, and
>the fact that the fossil tracks match underwater prints much better than
>dry, crumbly, wet or very wet sand ones.
>
Any competent geologist can spot the difference between a fossil sand dune
and a fossil sand bar, based partly on studies of modern sand dunes and sand
bars. The eolian nature of the Coconino sandstones was recognized in the
1930's, but modern research has verified that conclusion. There is no doubt
among geologists that the Coconino is made up of petrified sand dunes, not
petrified sand bars.
>
>> Why should anyone who is not defending a literalistic interpretation of
>>the Bible, accept the rather bizarre flood model for the origin of this
>>formation over the straightforward one?
>>
>Why? Because the tetrapod tracks, invertebrate tracks, lack of body
>fossils, and sandstone made up of well-sorted rounded quartz sand is
>consistent with a submarine sand dune environment.
>
This largely superficial description of the Coconino does not begin to
describe the evidence that demonstrates the eolian nature of the sandstone.
For an excellent review, see "Coconino Sandstone" by LT middleton, DK
Elliott and M Morales in _Grand Canyon Geology_ (1990), edited by SS Beus
and M Morales. It also includes a discussion of the sandstone's ichnology.
The authors conclude, among other things, that the trace fossils establish
that the sand had been very dry except for occasional moistening by rain or
dew. They report no evidence that the Coconino had been submerged at any
time in its history.
Kevin L. O'Brien