Message Not Delivered: evolution-digest V1 #1298
PostMaster (Mailer-Daemon@navyouth.org)
Fri, 12 Feb 1999 10:13:04 -0700
The message you sent could not be sent to the following recipient(s):
SMTP:bgmsm@navyouth.org
Original Message Follows:
=========================
evolution-digest Friday, February 12 1999 Volume 01 : Number 1298
----------------------------------------------------------------------
Date: Thu, 11 Feb 1999 09:25:46 -0800
From: "Arthur V. Chadwick" <chadwicka@swau.edu>
Subject: Cambrian Explosion
I posted a couple of papers earlier tha I thought were worthy of comment.
Kevin's recent discussion on the naturalistic imperative of science brings
back to mind these statements on the origin of complex life forms. Since
the sources were in the earlier communications, I simply include a couple
fo crucial paragraphs for consideration
" If the results of his team's genetic study are correct,
Hedges says the scientific question must change from "How
did all these species evolve so suddenly early in the Cambrian
period?" to "Why don't we see any fossils of these species
long before the Cambrian period?" Among the suggested
answers are that changes in the Earth's atmosphere led to
the development of hard external skeletons in animals that
had only soft external skeletons before the Cambrian period.
"Hard body parts like external skeletons are most likely to
become fossils," Hedges explains. Species not likely to
fossilize, like earthworms, typically live and die without
leaving a trace of their existence--except in the genes of
their descendants. "
> "Some scientists have theorized that the ancestors of creatures that
>suddenly and mysteriously appeared in the Cambrian era may have been
>boneless creatures that could not be captured in the fossil record. But
>this explanation for a pattern of Darwinian evolution is weakened by the
>presence of soft-tissued fauna in the China fossils, and the persistent
>absence of those forms, or those of ancestors of them, in the earlier
>geological record also available at the Chengjiang site. Professor Chen
>insisted that the biological ãexplosionä exhibited at Chengjiang is not
>an illusory artifact of an incomplete fossil record, but an accurate
>preservation of the true history of life on earth. Accordingly,
>biologists should construct theories of lifeâs origin in light of this
>paleontological evidence, not in spite of it."
Where will naturalistic science go with this?
Art
http://geology.swau.edu
------------------------------
Date: Thu, 11 Feb 1999 13:34:46 -0600
From: "Karen G. Jensen" <kjensen@calweb.com>
Subject: Re: Flood Model and ichnofossils
>Kevin O'Brien wrote:
>
>> [snip]
>>
>> >
>> >>...and how do the tiny little reptiles survive this process?
>> >
>> >A lot of them probably died. But enough of them survived that during the
>> >Coconino depostion they were able to leave millions of trackways.
>> >
>>
>> Millions survived? Or are you saying a dozen (figuratively speaking; the
>> exact number is immaterial as long as it was low) were so energetic (despite
>> malnutrition and unimaginable stress) that they scampered all over the
>> exposed sediments, virtually non-stop, until they finally drowned?
>
>This is the key problem that the Coconino poses for flood geology. We are
>supposed to imagine that the animals that left those trackways:
>
>A. managed to survive the downpour of so much rain that the continents were
>virtually wiped clean;
Later, yes; but not before the Permian deposition. The Permian may be only
a few days or weeks into the Flood, before the major land areas were eroded
(most truely land-plant fossils and land animals are in Mesozoic and higher
strata).
>B. managed to avoid dying in the astounding turmoil of that much water flowing
>to and fro;
Many died, to be sure. Most bottom dwelling life (trilobites, brachiopods,
etc.) was already buried, even extinct.
>C. managed not to be buried while several thousand feet of sediment was laid
>down in the canyon (in alternating layers of sandstone, limestone, and shale -
>another enormous problem to explain) at a rate measured in feet per hour; and
Interesting that the order of these vast layers is: sandstone (Tapeats),
shale (Bright Angel), limestone (Muav, Redwall), then sand (Supai), shale
(Hermit), then sand (Coconino), with limestone (Kaibab) on top -- three
mega-pulses of coarse to fine sediments, now eroded and exposed in the
Canyon.
>D. managed to breathe and find food while all of this is going on.
>
Water cushions shear forces. Whatever energetic deposition was going on
beneath those that could float could be safe as a boat.
>How did spiders of all things manage to live through that?
Spiders probably couldn't, at all! But without body fossils, the
interpretation of the invertebrate tracks as representing spiders is very
insecure.
And if the sediment
>was being laid down so incredibly fast, why are there no body fossils
>trapped in
>the sandstone?
The depositional conditions were apparently optimal for a small range of
particle sizes, that of the sand grains.
This is, of course, in addition to the clear evidence of
>terrestrial deposition in the Coconino - the composition of the sand
>particles,
>the sorting, the angle of the sand, etc.
Have you seen the line graphs comparing grain size distributions (grain
size vs cumulative frequency percent) for desert sand dune, offshore
estuary sand, estuary sandwaves, and the Coconino sandstone? The coconino
profile most closely matches the profile of the estuary sandwaves (Altamaha
Estuary in Georgia), with larger grainsize in the Coconino.
I don't see any way that someone can
>make the argument that the Coconino was deposited underwater and treat the
>evidence honestly.
>
There are lots of things that we don't see. None of us have seen all that
data. It will be very interesting to see the truth of this if we are ever
so priviliged as to see it. I hope all of us can stay humble though it all!
Karen
------------------------------
Date: Thu, 11 Feb 1999 13:34:56 -0600
From: "Karen G. Jensen" <kjensen@calweb.com>
Subject: Re: Flood Model and ichnofossils
>[snip]
>
>>
>>>...and how do the tiny little reptiles survive this process?
>>
>>A lot of them probably died. But enough of them survived that during the
>>Coconino depostion they were able to leave millions of trackways.
>>
>
>
>Millions survived? Or are you saying a dozen (figuratively speaking; the
>exact number is immaterial as long as it was low) were so energetic (despite
>malnutrition and unimaginable stress) that they scampered all over the
>exposed sediments, virtually non-stop, until they finally drowned?
>
>Why didn't snakes survive with them, or toads, or turtles, or field mice?
>
The Coconino Sandstone is Permian, before the Mesozoic deposition brought
in and fossilized an abundance of land-dwelling organisms.
Karen
------------------------------
Date: Thu, 11 Feb 1999 13:17:03 -0600
From: "Karen G. Jensen" <kjensen@calweb.com>
Subject: Re: Flood Model and dinosaur tracks
>>
>
>[snip]
>
>>
>>>Dinosaur tracks are not found down near the
>>>base of the Cambrian (the earliest "flood" sediments). They are found
>only in
>>>Mesozoic-age rocks. Mesozoic rocks in the western U.S. typically have
>>>thousands
>>>of feet of Paleozoic age rocks beneath them. Those Paleozoic rocks are
>>>presumably
>>>flood sediments. Those dinosaurs had to leave tracks after MOST of the
>flood
>>>sediments HAD ALREADY BEEN DEPOSITED. Presumably after the highest
>>>mountains
>>>had been covered by flood waters leaving the poor dinosaurs no place to
>>>walk to in their escape.
>>
>>Right. And different dinosaurs were deposited in different layers (some
>>middle Jurassic, others Upper Cretaceous, etc.) because of differences in
>>their success in evading the waters for a time, different strength and
>>endurance in swimming ability, different floatational characteristics, etc.
>>
>
>
>Then why are Tyrannosauroids and Allosauroids not deposited together? Being
>of similar size and body plan, you would expect that they would have been
>very similar in all the considerations you name above, yet they are found in
>the fossil record as much as 100 million years apart.
Evidently these two did not live near each other. And if they had, we
would expect that they would have competed, and we know which one we would
predict as the winner. Geographic distribution is more important than body
size, floatation, etc. for fossil distribution. I should have noted that
above.
Same thing with
>regard to Ankylosauroids and Stegosauroids.
Yes, same thing.
Why are the Ceratopsians spread
>across 50 million years instead of all being found in the same-age
>sediments? Same thing with the Hardosaurs.
Same thing, with the floatational considerations.
Why is the Andrewsarchus not
>found with bear fossils, or Arsinoitherium with rhinoceros fossils, or
>Phorusrhacos with ostrich fossils?
>
Good question. Where were the Tertiary forms when the Mesozoic ones were
being fossilized? The standard evolutionist answer: They hadn't evolved
yet. The standard creationist answer: Well, uh, they were in the
highlands somewhere... (or in icebergs, or all in the ark, or....) The
truth -- ah, I look forward to knowing the truth on this! -- may be
somewhere between these extremes.
The Tertiary forms did expand after the Mesozoic forms went extinct (or
most of them -- many Mesozoic plant genera/subfamilies, and a few animals,
are extant, tho given different names). The Neogene (Upper Tertiary)
really does look to me like postflood speciation, (fossilized during
volcanic events, quakes, floods, etc continuing for a time after the
flood).
>It won't work; too many modern and extinct animals are close enough in size
>and body design to have been deposited together according tour model, yet
>are actually found to be quite far apart.
Yes, floatation is only one aspect of taphonomic dispersal. I shouldn't
have presented it without noting other factors as well. Just like
hydrodynamic sorting, alone it can't explain everything, or any other
factor taken by itself.
We don't have all the answers at all. Thank you for pointing out obvious
errors.
Karen
------------------------------
Date: Thu, 11 Feb 1999 13:31:58 -0600
From: "Karen G. Jensen" <kjensen@calweb.com>
Subject: Re: Flood Model, batholiths, and science
>>
>>Dear Steve,
>>
>>To finish up this one,
>>
>
>[snip]
>
>>
>>> Well, that's not science. The calculations governing cooling of rock
>>>are pretty
>>>straightforward and postulating some "missing major factors" that would
>>>overturn
>>>all we know about thermodynamics and the laws of physics is simply wishful
>>>thinking.
>>
>>Maybe so. But I am still open to the thought that something as unexpected
>>as plate tectonics was may come to light, that explains the earth's heat
>>balance in terms we haven't thought of yet. I don't want to be
>>closed-minded on this.
>>
>
>It's not a matter of being close-minded; it's a matter of recognizing that
>your unknown "major factors" would violate the known laws of thermodynamics
>and physics, and so are going to be virtually non-existant.
Isn't that what they were saying when Wegner and a few before him suggested
continental movement? And in physics when they thought that they had the
laws described, and there was little to do but confirm them? They had no
idea that there could be any other way to look at things, and basically
denied the possibility.
New data, unexpected experimental results, changed the picture. What that
teaches me is that we probably don't know everything right now, either, and
perspectives may change still.
What I find
>interesting is that your final statement could have been said by someone
>claiming to have a perpetual motion machine that operates by principles not
>yet known to science. All one would have to do is replace "explains the
>earth's heat balance in terms we haven't thought of yet" with something like
>"explains how to to get usable energy from empty space".
>
I often have to explain to people (when they watch the water wheel and/or
the Foucault Pendulum in the Nature Center here) that there is no such
thing as a perpetual motion machine. They always seem to be hoping that
there is! If that is the way you see my viewpoint on the fossil record, I
appreciate your patient tolerance!
Karen
------------------------------
Date: Thu, 11 Feb 1999 17:39:16 -0700
From: "Kevin O'Brien" <Cuchulaine@worldnet.att.net>
Subject: Re: Flood Model and ichnofossils
>>>
>>>>...and how do the tiny little reptiles survive this process?
>>>
>>>A lot of them probably died. But enough of them survived that during the
>>>Coconino depostion they were able to leave millions of trackways.
>>>
>>
>>
>>Millions survived? Or are you saying a dozen (figuratively speaking; the
>>exact number is immaterial as long as it was low) were so energetic
(despite
>>malnutrition and unimaginable stress) that they scampered all over the
>>exposed sediments, virtually non-stop, until they finally drowned?
>>
>>Why didn't snakes survive with them, or toads, or turtles, or field mice?
>>
>
>The Coconino Sandstone is Permian, before the Mesozoic deposition brought
>in and fossilized an abundance of land-dwelling organisms.
>
How does this statement answer either of my observations?
Kevin L. O'Brien
------------------------------
Date: Thu, 11 Feb 1999 18:30:17 -0700
From: "Kevin O'Brien" <Cuchulaine@worldnet.att.net>
Subject: Re: Flood Model and dinosaur tracks
You ignored the most serious error of all.
>>>
>>>Right. And different dinosaurs were deposited in different layers (some
>>>middle Jurassic, others Upper Cretaceous, etc.) because of differences in
>>>their success in evading the waters for a time, different strength and
>>>endurance in swimming ability, different floatational characteristics,
etc.
>>>
>>
>>
>>Then why are Tyrannosauroids and Allosauroids not deposited together?
>>
"Deposited together" does not mean that an allosauroid and a tyrannosauroid
were buried side-by-side like in a family cemetary plot. It means that they
were buried in sediments that evolutionists would say have the same age.
Because allosauroids and tyrannosauroids are of the same size and have the
same body plan, they should have both shared the same "success in evading
the waters for a time", the same "strength and endurance in swimming
ability", the same "floatational characteristics, etc". As such, they
should have been buried in the same-age sediments, regardless of whether
they lived together or not. The same would be true for the ankylosauroids
and the stegosauroids, the ceratopsians, the hardosaurs, Andrewsarchus and
bears, Arsinoitherium and rhinoceros, and Phorusrhacos and ostriches.
>>
>>Being
>>of similar size and body plan, you would expect that they would have been
>>very similar in all the considerations you name above, yet they are found
in
>>the fossil record as much as 100 million years apart.
>
>Evidently these two did not live near each other.
>
Irrelevant. If they shared the same survival characterists they should have
ended up in same-age sediments, regardless of whether they lived near each
other or not. However, the fossil record demonstrates that in fact both
inhabited the same regions of the world (such as North America), both hunted
in the same environments and both preyed on the same kinds of animals. Had
they been contemporaries they would have both shared the same geographical
distribution.
>
>And if they had, we would expect that they would have competed....
>
Not necessarily. Lions and tigers both share the same range in India, yet
they do not compete. Grizzly and black bears share the same range in the
West (or used to) yet do not compete. Hyenas and lions share the same range
in Africa, but not compete except for occasionally stealing each other's
kills. In point of fact, predators of the same size and strength rarely
compete directly with one another under normal conditions, so there is no
reason to expect that allosauroids and tyrannosauroids would have as well.
>
>...and we know which one we would predict as the winner.
>
Not necessarily. The evidence suggests that allosauroids were group
hunters, whereas the tyrannosauroids were solitary or hunted as pairs of
siblings or mates. They would have sort of been like wolves and grizzly
bears, except for the size differential. A pack of allosauroids could have
easily dispatched a single or pair of tyrannosauroids if they wanted to. I
doubt they would have tried; there would have been no reason for it.
>
>Geographic distribution is more important than body
>size, floatation, etc. for fossil distribution. I should have noted that
above.
>
As I have shown this is irrelevant to whether they should be found in the
same-age sediments.
>
>>Same thing with regard to Ankylosauroids and Stegosauroids.
>
>Yes, same thing.
>
Again, the fossil record shows that they would have shared the same
geographical distribution.
>
>>Why are the Ceratopsians spread
>>across 50 million years instead of all being found in the same-age
>>sediments? Same thing with the Hardosaurs.
>
>Same thing, with the floatational considerations.
>
And again, the fossil record indicates that all the different ceratopsians
would have shared the same geographical distribution. And they all would
have shared the same floatational characteristics. Ditto for all the
different hadrosaurs.
>
> Why is the Andrewsarchus not
>>found with bear fossils, or Arsinoitherium with rhinoceros fossils, or
>>Phorusrhacos with ostrich fossils?
>>
>
>Good question. Where were the Tertiary forms when the Mesozoic ones were
>being fossilized? The standard evolutionist answer: They hadn't evolved
>yet. The standard creationist answer: Well, uh, they were in the
>highlands somewhere... (or in icebergs, or all in the ark, or....) The
>truth -- ah, I look forward to knowing the truth on this! -- may be
>somewhere between these extremes.
>
Or on floating mats of vegetation. Considering the ad hoc nature of the
creationist answers, the evolutionary answer sounds more plausible,
especially when you realize the the radiometric ages given to the various
sediment layers are fairly accurate.
>
>The Tertiary forms did expand after the Mesozoic forms went extinct (or
>most of them -- many Mesozoic plant genera/subfamilies, and a few animals,
>are extant, tho given different names). The Neogene (Upper Tertiary)
>really does look to me like postflood speciation, (fossilized during
>volcanic events, quakes, floods, etc continuing for a time after the
>flood).
>
So if Andrewsarchus and bears evolved from the same common ancestor off the
Ark, as did Arsinoitherium and rhinoceroses, and Phorusrhacos and ostriches,
how is that any different from standard evolutionary theory, except for the
time differential? And why did Andrewsarchus, Arsinoitherium and
Phorusrhacos subsequently go extinct when bears, rhinoceroses, and ostriches
did not?
>
>>It won't work; too many modern and extinct animals are close enough in
size
>>and body design to have been deposited together according tour model, yet
>>are actually found to be quite far apart.
>
>Yes, floatation is only one aspect of taphonomic dispersal. I shouldn't
>have presented it without noting other factors as well. Just like
>hydrodynamic sorting, alone it can't explain everything, or any other
>factor taken by itself.
>
>We don't have all the answers at all. Thank you for pointing out obvious
>errors.
>
The fatal error to you model is that these animals would have shared all
characteristics that would have sorted them from other drowned animals, so
they should have ended up in the same-age sediments, yet they did not. The
most obvious reason why they did not is because they were not
contemporaries; ie, they lived at very different and sometimes widely spaced
times.
Kevin L. O'Brien
------------------------------
Date: Thu, 11 Feb 1999 18:41:19 -0700
From: "Kevin O'Brien" <Cuchulaine@worldnet.att.net>
Subject: Re: Flood Model, batholiths, and science
>>>
>>>Maybe so. But I am still open to the thought that something as
unexpected
>>>as plate tectonics was may come to light, that explains the earth's heat
>>>balance in terms we haven't thought of yet. I don't want to be
>>>closed-minded on this.
>>>
>>
>>It's not a matter of being close-minded; it's a matter of recognizing that
>>your unknown "major factors" would violate the known laws of
thermodynamics
>>and physics, and so are going to be virtually non-existant.
>
>Isn't that what they were saying when Wegner and a few before him suggested
>continental movement?
>
No. The problem with Wegner's continental drift model was that he could not
propose a mechanism that could move the continental plates. Most geologists
did not believe such a mechanism was possible, but no one claimed that such
a mechanism would violate known laws.
>
>And in physics when they thought that they had the
>laws described, and there was little to do but confirm them? They had no
>idea that there could be any other way to look at things, and basically
>denied the possibility.
>
This is too vague to comment on. Can you give any specific examples?
>
>New data, unexpected experimental results, changed the picture. What that
>teaches me is that we probably don't know everything right now, either, and
>perspectives may change still.
>
But there has never, to my knowledge, been a case when a physical law was
found to be false by new evidence. All theories that violate known physical
laws are proven wrong in time.
>
>>What I find
>>interesting is that your final statement could have been said by someone
>>claiming to have a perpetual motion machine that operates by principles
not
>>yet known to science. All one would have to do is replace "explains the
>>earth's heat balance in terms we haven't thought of yet" with something
like
>>"explains how to to get usable energy from empty space".
>>
>I often have to explain to people (when they watch the water wheel and/or
>the Foucault Pendulum in the Nature Center here) that there is no such
>thing as a perpetual motion machine. They always seem to be hoping that
>there is! If that is the way you see my viewpoint on the fossil record, I
>appreciate your patient tolerance!
>
Only when you say that results which prove your model wrong in fact can be
explained away by invoking unknown considerations, which are invariably ad
hoc and often contradictory.
Kevin L. O'Brien
------------------------------
Date: Thu, 11 Feb 1999 20:34:30 -0600
From: Bill Payne <bpayne15@juno.com>
Subject: Re: Flood Model [was Early Cambrian explosion]
Well said, Ed. I appreciate your commets.
Bill
On Tue, 09 Feb 1999 17:43:21 -0500 Ed Brayton <cynic@net-link.net>
writes:
>Art, I'm really surprised to hear you say this. If the position it
>implies is
>really what you meant, my respect for you will drop quite a bit. There
>is no
>question that every scientist works within a theoretical framework and
>that
>evidence gets filtered through that paradigm. No one disputes that,
>but I have
>to disagree with the implications of the rest of this paragraph.
>First,
>Steve's position was that you and your colleagues are selectively
>reporting the
>evidence. You don't dispute that, and in fact you seem to admit that
>this is
>the case. Do you think that selectively reporting evidence, and
>ignoring
>evidence against your thesis, is A) honest and B) an effective way of
>discerning whether the thesis is correct? Does the fact that your
>thesis is a
>minority position free you from the burden of dealing with the
>totality of the
>evidence in an honest way?
>
>I also cannot accept the idea that two groups of scientists advancing
>their
>theses, without regard to an honest search within the two camps to
>determine
>whether their thesis is correct, helps science advance. The tone of
>your
>statement here reminds me very much of when I coached competitive high
>school
>and college debate. Because a person had to be both the affirmative
>and the
>negative during a tournament, he is forced to take positions he
>disagrees with.
>In the confines of that game, the only way to defend a position that
>you don't
>agree with is to quote selectively from the evidence and be
>disingenuous. But
>that was a game, and the goal was to win, not to discern which
>position is
>true. Is it really your position that two sides, both acting
>disingenuously and
>selectively reporting the evidence, somehow advances science? Who is
>to act as
>the judge in this contest?
>
>I would argue that not only can a person advocate a thesis without
>selectively
>reporting the evidence, but that if that person wants his thesis to be
>an
>accurate representation of reality, he or she MUST consider the
>totality of the
>evidence. What else are we left with? Do you consciously ignore
>contrary
>evidence and advance the thesis regardless of it? It seems to me that
>this is
>the reverse of how scientists should operate. Rather than picking a
>thesis to
>advance and then reporting whatever evidence can be made to seem as
>though it
>supports that thesis, one should look at the evidence and then develop
>a thesis
>that explains it. I'm not arguing for some sort of pure objectivity
>among
>scientists, of course, but I think there is a realistic middle ground
>between
>that and what you appear to be advocating, the notion that two
>opposing camps
>acting in a disingenuous manner somehow advances science toward the
>correct
>conclusion.
>
>Ed
>
>
>
___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]
------------------------------
Date: Thu, 11 Feb 1999 20:07:37 -0800
From: Pim van Meurs <entheta@eskimo.com>
Subject: RE: Flood Model, batholiths, and science
>It's not a matter of being close-minded; it's a matter of recognizing =
that
>your unknown "major factors" would violate the known laws of =
thermodynamics
>and physics, and so are going to be virtually non-existant.
Isn't that what they were saying when Wegner and a few before him =
suggested
continental movement? And in physics when they thought that they had =
the
laws described, and there was little to do but confirm them? They had =
no
idea that there could be any other way to look at things, and basically
denied the possibility.
New data, unexpected experimental results, changed the picture. What =
that
teaches me is that we probably don't know everything right now, either, =
and
perspectives may change still.
Right, anything may change but wishful thinking is the last one to =
achieve such a change. Especially if your "unknown factors" are in =
violation of known laws.
------------------------------
Date: Thu, 11 Feb 1999 20:08:44 -0800
From: Pim van Meurs <entheta@eskimo.com>
Subject: RE: Cambrian Explosion
Where will naturalistic science go with this?
Is there any other science ? I doubt it.
------------------------------
Date: Fri, 12 Feb 1999 18:21:12 +1100
From: Jonathan Clarke <jdac@alphalink.com.au>
Subject: Re: Flood stratigraphy (was Flood Model and dinosaur tracks)
Dear Karen
Karen G. Jensen wrote (in part):
> No, you got it right. I see the worldwide water catastrophe as extending
> at least from the pC-C (Cambrian) boundary to at least the K-T. (So the
> K-T crisis is part of the C-T catastrophe.)
>
>
Are you saying that you believe PC rocks are pre-flood, C-K rocks flood and
Cainozoic rocks post flood?
If you do then you must hold two things: First that biostratigraphy is valid
(the
only way we can say that a rock is PC, C-K, Ca etc.). Second that the numerical
ages from radiometric dating are internally consistent, that a rock that has a
numerical age >540 Ma is always pre-flood (even if it's actual age is only >4200
yrs by a literalistic chronology) rocks with numerical ages of 540-65 Ma are
always
flood (4200-4199 yrs), and those <65 Ma are post-flood (<4199 yrs).
Am I correct, or have I missed your point entirely?
> Karen
In Christ
Jonathan
------------------------------
Date: Fri, 12 Feb 1999 20:26:34 +1100
From: Jonathan Clarke <jdac@alphalink.com.au>
Subject: Re: Flood Model and reefs
Dear Karen
Karen G. Jensen wrote (in part):
> Currently as far as I am aware, the most accepted model for Capitan Reef is
> that it is an underwater bank. I have heard that there is a new publication
> coming out this spring as SEPM Concepts in Sedimentology and Palentology
> No. 8, entitled "Geologic Framework of the Capitan Reef" the editors are
> Art Saller and Paul M Harris. It will probably present a variety of
> opinions.
The difference between a reef and a bank is often one of degree and/or
semantics.
The Great Bahama Bank has fringing reefs, for example. The Capitan structure
contains evidence of shallow water construction, abundant sea floor cementation,
and evidenc of significant relief above the seafloor, especially the basin.
This
sounds like a reef to me. For something that size reef or bank complex may be a
better term.
> Aside from Capitan Reef, other structures once interpreted as reefs have
> been reinterpreted as debris flows. For example, you could look at
> Mountjoy EW, Cook HE, Pray LC, McDaniel PN. 1972. Allochthonous carbonate
> debris flows worldwide indicators of reef complexes, banks or shelf margins
> Stratigraphy and Sedimentology, International Geological Congress, 24th
> Session, Section 6, p 172-189, which describes five examples.
Of course there are some things that have been called in situ reefs in the past
which are now recognised as debris flows. Why were they identified as reefs?
Because they are made of of reef rocks which are characteristically organically
bound limestones and/or with abundant evidence of early cementation. But where
did
those blocks come from? From parental reefs, or reef environments where there
was
not large single reef mass, but a collection of patch reefs, some of which ended
up
sliding down into deeper water. In every case that I know of, including the
paper
you cite, the blocks in the debris flow blocks (some of which are huge-live
climbed
some of them) were transported down slope by mass movement from the main reef
mass where they were formed. In some cases the original reef they came from is
exposed, in some cases not. For every "reef" now identified as a transported
block
there are dozens or hundred recognised as being in place. Every block of
transported reef rock points to a precurssor reef.
> Karen
In Christ
Jonathan
------------------------------
Date: Fri, 12 Feb 1999 20:26:40 +1100
From: Jonathan Clarke <jdac@alphalink.com.au>
Subject: Re: Halite layers, and GVS
Dear Karen
Karen G. Jensen wrote (in part):
> Dear Jonathan,
>
> Thank you for your interesting observations on those Australian reefs.
> I've sent part of it to a friend who knows much more about reefs (live and
> fossil) than I do. Waiting for his comments.
Yes, they are interesting, aren't they? We will see what he comes up with.
> >Thin halite layers are very common in salt lakes. In most it redissolves
> >when the lakes flood, but not always. Lake McLeod has several m of permanant
> halite,
> >deposited by sewater seepage from the Indian Ocean.
>
> Is the structure of that halite layer like that of the giant layers in the
> geological record? Do you believe that giant layers formed in coastal
> areas where salt water seeped in and was concentrated by surface
> evaporation?
I had hoped that I would be able to look up the standard work on Lake MacLeod in
the library today, but alas! alack! it was out on loan. If you are really keen
to
find out more about Lake MacLeod let me know next week when I can get the book.
Australia, just north of Shark Bay. It is a fault bound depression about 30
km
wide and 100 km long, slightly below sea level and separated from the Indian
Ocean
by a porous barrier of Pleistocene sands and limestones. Sea water seeping
though
the barrier discharges via springs into the lake and evaporates forming the salt
deposits. There are some12 m of halite in the lake, plus gypsum and limestone.
I
can't remember whether the halite is depositing now but it certainly has done so
in
the recent past.
> > Halite is also forming at >the bottom of the Dead Sea.
>
> How do the characteristics of this halite compare with those under Lake
> McLeod, and those in the geo record?
Halite in the Dead Sea forms into three main environments. The first is in the
shallow water at the southern end, the second is the deep water of the main
basin,
and the third is interstitially in shoreline sediments of other compositions.
The
halite in the first environment resembles that formed in other shallow water
environments today (Lake MacLeod, etc.). The deep water halite is fine-grained,
well laminated, and associated with laminated carbonates and gypsum. I
understand
that parallels have been drawn with laminites in ancient units such as the
Castile
Formation in the Permian of the US. The interstitial halite forms large cubes
in
mud, and thus resemble some impure halite deposits such as those of the
Cambrian
of South Australia.
> >Thicker deposits are more difficult to get, but to occur today. There is over
> 900 m of very pure halite in Salar de Atacama in northern Chile. The halite is
> still forming, albeit slowly. Certainly
> >there is nothing like the saline giants being deposited today, but the
> mechanisms are
> >there and understood, it is just the scale that is different.
> >
>
> What reasons are suggested to explain the past/present difference in scale?
It takes an unusual coincidence of geographic, climatic, and tectonic
circumstances to get a saline giant. That is why they are rare. Details vary
from
basin to basin, but you need an excess of evaporation over precipitation, a
deep
or actively subsiding basin, slow rates of sediment input and a water inflow
with
little or no outflow. The most recent time this happened (for us conventional
geologists) was in the Miocene when the Mediterranean dried out repeatedly.
There
was others in the Jurassic (South Atlantic), Permian (Europe) Devonian
(Canada/US)
and other intervals I am sure I have forgotten. The overall processes of
evaporite
formation are scale independent.
> And now, to get back to the GVS:
>
> It is available from University Microfilms International (Ann Arbor, Michigan).
> The dissertation is on fossil pollen and spores of the GVS (1987). A
> summary of the geological characteristics is in Appendix A (pp.110-128) --
> just a side issue (I went to the library one day to look up the geological
> history of the sequence, and spent several months discovering the history
> of geologists' radically changing views of the geological history of the
> sequence!)
Thank you. Its always interesting to follow through the history of ideas about
a
particular formation.
> >Individual turbidites are of course deposited rapidly, but the lime between
> >depositional events is highly variable. If there are long periods between
> >individual events one would expect things like burrowing (providing the
> >bottom or pore waters were not anoxic), erosion surfaces, even hardgrounds.
> >Certainly the turbidite successions I have seen contain these features. They can
> be very
> >subtle though,
>
> You might expect some deposition, too. Hard to imagine much time with none.
You can get thousands of years with no deposition quite easily. There areas of
relict sediments on many continental shelves today. In clastic marine
sediments,
long periods of non deposition will be marked by horizons enriched in iron,
manganese, phosphate, glauconite, etc. They are often well burrowed. With
carbonates these horizons are generally lithified crusts, called hardgrounds,
which tend to be bored, rather than burrowed. Whether this is applicable to
your
section, I don't know.
> >However you can't use the fact that the limestone beds were folded
> >and not brecciated as evidence of rapid deposition. All this is evidence
> >of is lack of induration as your correctly point out. Deep water limestones,
> >especially fine-grained ones, lithify very slowly. We know this from deep sea
> >cores. Of course, even indurated limestones can fold very nicely if the
> >conditions are right.
> >
> The Great Valley Sequence is 10 to 20 km thick. The lower part is
> considered to be Tithonian (Upper Jurassic) and the higher parts Turonian
> and on up to Maastrictian (Upper Cretaceous) and even Danian (Lower
> Paleocene). This is usually described as representing about 80 million
> years. The folded areas I saw were in a locality in the lower portion, but
> the folding probably happened in conjunction with the tilting of the entire
> sequence (after it had finished being laid down horizontally). Do you
> believe induration could wait many millions of years?
Several components here to your question. As I understand you, your argument
runs
like this: The thin limestone beds are not brecciated. Thus they must have
been
soft when deformed. Yes, it is possible for sediments to remain uncemented for
many millions of years, especially if only shallowly buried. Obviously not the
case with your sediments though (12 km is not shallow burial to me!). You say
that
the sequence was completely deposited before deformation began. With 12 km of
burial I imagine things would be quite lithified but at those sort of depths
brittle beds start deforming in a ductile manner. Your rocks should have been
metamorphosed to lower greenschist metamorphic facies. Is this the case?
> To me it looks like mega-deposition and mega-tilting, but not mega-time.
> Consistent with Genesis 7-8.
No Karen, not consistent with Genesis 7-8, but with only what with your reading
is
of it. My Bible does not say anything about mega deposition or mega tilting.
>
>
> Your sister in Christ,
>
> Karen
In Christ
Jonathan
------------------------------
End of evolution-digest V1 #1298
********************************