Re: marine or eolian dunes?

Glenn Morton (
Tue, 03 Feb 1998 20:50:29 -0600

At 07:51 AM 2/3/98 -0800, Arthur V. Chadwick wrote:

>That work was done in the 1940's, before anyone had even thought of
>subaqueous for Coconino. If you had read Brand and Tang (and especially
>Tang's thesis), you would see that all these issues have been adequately
>addressed. The trackways of the "arthropod" (which could as well be
>crustacean as a scorpion), could not possibly have been made on dry sand,
>since the distinct marks could not have survived on a foreset slope of a
>dune in dry sand.

I don't think the suggestion is that the tracks were made in dry sand. The
suggestion was that they were made in damp sand. I think most would agree
that you can't make good tracks in absolutely powder dry sand.

>>I don't think glauconite implies deepwater deposition. It is found quite
>>abundantly in the coastal plains sediments of the eastern United States and
>>those are generally considered to be relatively shallow water deposits. But
>>they were MARINE. (see N. Spoljaric "Geology of the Delaware Coastal Plain",
>>in John C. Kraft and Wendy Carey, ed. Trans. Delaware Acad. of Sci. 7, 1976,
>>pp 93-95)
>You stand nearly alone on that one. In the modern environment, the
>formation of glauconite requires deep water. If you want to suggest that
>in the past, glauconite was formed in shallow water (as Chafetz has done in
>his article you would love, "Depositional, shallow water precipitation of
>glauconite: the present is not the key to the past" in GSA Abs w
>prog:28:109) the burden of proof is on you. To say that a supposed shallow
>water deposit containing glauconite is proof that glauconite formed in the
>past in shallow water without reevaluating the basis for the attribution of
>"shallow water" does not help. I reassert: glauconite is a deep water
>environmental indicator.

Judging by where the deposits are (up on top of the buried Appalachians),
judging by their association with coal, this is a shallow water deposit.
And I do not stand as alone as you might think.

"Glauconite is a mineral which is widely believed to form only in marine
environments and to be so unstable that it cannot survive re-working. It
is therefore held to be diagnostic of marine rocks. This criterion is not
infallible. Detrital glauconite occurs in fluviatile Neogene red beds in
the Dead Sea Valley. As a general rule however glauconite is a useful
indicator of marine environments and studies of the present day distribution
of glauconite suggest that it may be possible to narrow down the precise
conditions which limit its formation."~R. C. Selley, "Ancient Sedimentary
Environments" 2nd ed. 1978, p. 8


"Glauconite is a complex mineral related to the clays and the micas;
essentially it is an aluminosilicate containing magnesium, iron, and
potassium. Glauconite occurs as a replacement of faecal pellets and as an
internal mould of forams and other small voids. Detailed discussion of the
genesis of glauconite in modern sediments will be found in Odin and Bjerkli
and Ostmo-Saeter. Prrenga has revied the environmental parameters of
glauconite formation.
"The consensus of opinion is that glauconite forms only as an
authigenic mineral during the very early diagenesis of marine sediment.
Penecontemporaneous reworking can concentrate glauconite in shoal sands and
transport it into deeper basinal sands." ibid p. 26

Krauskopf, Introduction to Geochemistry, 1967 writes:

"Under mildly oxidizing conditions in shallow seas, ferric iron may go into
glauconite [approximately KMgFe(SiO3)3*3H2O], and near hot springs (perhaps
sometimes also as a result of ordinary weathering) into jarosite[...]." p. 110

None of these say anything about deep water. And Dot and Batten, 1988
Evolution of the Earth, p. 290 merely say that it requires slow deposition.
Some of the past epeiric seas where shallow and had slow deposition. And as
you know depositional speed is not restricted only to deep waters.

>>Please continue. That is hardly enough to explain these things. It seems to
>>me that there is more of a problem with mixing in a global flood when
>>everything is supposed to be eroded from the preflood world, then
>>redeposited. Surely there was some mixing of lime and clastics the likes of
>>which we don't see in an actualistic or uniformitarianistic world.
>Really, I was trying to get an explanation out of you... I have no
>difficulty with nothing happening for 260 million years if it was not 260
>million years. On the other hand, the Nubian SS gives us a chance to
>reevaluate everything about the nature of the fossil record and the meaning
>of the geological column. I am working on that.

I already said I didn't have an explanation for why 260 million years of
carbonate deposistion remained in one place with little clastic imput. But
since you find sand in the Redwall limestone (as you noted in another post)
why wouldn't the global flood give us more sand here? Oh well...


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