NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/talk/origins/15988

Text File | 1992-12-31 | 16.4 KB | 290 lines

Newsgroups: talk.origins
Path: sparky!uunet!nntp1.radiomail.net!fernwood!aurora!isaak
From: [e-mail] (Mark Isaak)
Subject: Response to the Response to the Flood FAQ, part 2
Message-ID: <[e-mail]>
Reply-To: [e-mail] (Andrew MacRae)
Organization: The Aurora Group
Date: Thu, 31 Dec 92 18:46:08 GMT
Lines: 279


[More contributions from Andrew MacRae, who himself can't post.]

3. FOSSIL SORTING and "STRATIGRAPHIC LEAK"
> [e-mail] (Wayne Folta)

>>[fossil sorting]

>This section of questions does raise difficulties.
    Oh?
>But no more difficulties than that spores and wood are found in Cambrian
>rocks (from Morris & Parker, quoting Weier, Stocking, and Barbour's
>textbook).

    Oh, ok, you want to avoid the question, and talk about supposed
"difficulties" in the conventional interpretation.  Fine.
    Ha!  If the original source of this information is what I think it
is, [Stainforth, 1966, Nature, v.210, p.292-294.] it is a clear case of
contamination.  I will elaborate further if this is the case.  Please let me
know what the original source of the information is.

I am a paleopalynologist - I study fossil pollen, spores, and microscopic
algae.  There are plenty of processes that can mechanically introduce
palynomorphs (i.e. the spores you mention) into otherwise barren rock.  You
can find a good summary of this in Traverse, 1988 (for instance): [Traverse,
A, 1988, Paleopalynology.  Unwin Hyman:Boston, 600pp.  The particular part
that discusses contamination problems is p.428].
        The basic problem is that spores and pollen are very durable and
very small, so they can be transported into cracks within the rock, with
little evidence of their transport.  Sometimes I find _modern_ pollen in my
sample preparations (easy to recognize because protoplasm is still present
inside!) despite careful cleaning of samples.
    However, the "wood" is intriguing, and I would like to know more
about what the authors claim.  There are some Precambrian plant tissues
reported from China, but they are not wood in the sense that they are from
land plants - they are from marine plants - "algae".  There are also
"spores" (in a very broad sense) of marine algae in Cambrian and Precambrian
rocks, but they are _very_ different from the spores of land plants.

>Also, Morris claims that fossils are found out of order, with the
>terminology "stratigraphic leak" applied to them.

    Yes, you and Morris are right, "stratigraphic leak" is a term for a
host of contamination problems that are observed.  However, you are implying
that there is no explanation, and that the occurrence of "stratigraphic
leak" somehow invalidates the majority of fossil occurrences that have no
such problems.  The explanation is simple, and even expected.  There are two
possible "out of order" conditions:
    1) anomalously "old" fossils in young rocks,
    2) anomalously "young" fossis in older rocks.
    The first is by far the most common.  For example, if you find a
dinosaur bone in a modern stream bed, it is condition 1.  It is a fairly
common occurrence, and happens because many fossils are durable (shells,
bones, plant spores, etc.), and have the potential to be eroded out of an
older rock sequence, and deposited in another, younger sequence.  This
process is called "reworking".  You see this happening _now_ if you go to a
bedrock outcrop where fossils are being eroded out of a cliff, and deposited
in beach sediments.  If the beach sediments are preserved, you will find
reworked, older fossils mixed in the modern sediments - potentially very
confusing if you are as simple-minded as Morris seems to think geologists
are.
    However, notice four features of the reworked fossils:
    1) They were embedded in older rocks, so they are probably
preserved in a different fashion from modern shells.
    2) They were eroded, so they should show signs of wear.
    3) They will be _mixed_ with younger fossils of a definite age (i.e.
the modern shells on the beach), so you will have fossils of two distinct
ages in one rock sequence.
    4) Since they have been eroded, many are destroyed before being
redeposited.  Usually the "in place" fossils are much more common than the
reworked ones.
    The fact is, in cases of "stratigraphic leak" with "older" fossils
in younger rock, some or all of these features are observed, and make it
clear that the "anomalously old" fossils are reworked.  Since you would
expect fossils to be reworked (since it happens in modern environments), it
is no surprise to geologists that it occurs in the past too.
    Reworking actually provides additional information to geologists,
since it indicates erosion of older rocks nearby.  This can be a useful tool
for working out the history of uplift in a mountain range beside a
depositional basin.  As predicted, reworked fossils in such a situation have
a reverse ordering because the youngest rocks at the top of the mountains
are eroded first, then deeper and deeper rocks.
    Reworked palynomorphs (fossil pollen and spores) are commonly darker
than the "in place" fossils, because they have been "cooked" in the
sediments for a longer period of time.  In my B.Sc. study [MacRae, R.  A.,
1989.  Palynology and stratigraphy of an upper Cretaceous
sedimentary-volcanic sequence, Emma Fiord, northwest Ellesmere Island,
N.W.T., Canada.  Unpublished B.Sc. thesis, Dalhousie University, Halifax,
Nova Scotia, 159 pages, 24 plates.] , I examined palynomorphs that were
deposited in Cretaceous sediments unconformably overlying a deeply weathered
limestone of Permian age.  I was not surprised to find a few very dark brown
Permian palynomorphs mixed with the light coloured Cretaceous ones.  In
partial confirmation of this, conglomerates in the Cretaceous sediments
contained chert pebbles that contained Permian age corals and foraminfera
with identical preservation to the underlying, in-place Permian cherty
limestones.
    The second condition, anomalously "young" fossils in older rocks, is
_very_ uncommon.  You don't, for instance, usually find Mesozoic dinosaur
fossils mixed with Cambrian trilobites.  In all the examples I have seen,
contamination of lower rocks by material from higher up is the explanation.
For example, some Ordovician or Silurian marine limestones in the central
U.S. contain what appear to be Carboniferous-age land vertebrates
(amphibians or reptiles, I can't remember).  No doubt Morris or other flood
creationists would jump on this as a clear anomaly.  However, the
explanation is again simple, since the land vertebrates occur in narrow
vertical crevasses in the limestone, filled with reddish terrestrial
sediments.  The interpretation is that they fell into the crevasses from
above, while the limestones were exposed to erosion during the
Carboniferous.  When spores are analyzed from the crevasse sediments, they
too are Carboniferous.
    Another common example of this condition is in oil wells.  As the
well is drilled deeper, chips of rock fall from the walls higher in the
borehole, and are eventually carried up the surface, and mixed with the
chips from the level the drill bit is currently penetrating.  This process
is called "caving".  When the microfossils in a sample of the chips are
examined, younger ones could be mixed in.  It is for this reason that
paleontologists working in wells use the _youngest/highest_ occurrence of a
fossil to work out the stratigraphy, rather than the oldest/lowest
occurrence.
    So, yes, "stratigraphic leak" is a problem, but it is not very
common, and it is easily recognizable because of other evidence left by the
processes responsible.

>Then there is the difficulty (for evolution) where tens or hundreds of
>millions of years of rocks are missing with no trace of weathering or other
>possible removal mechanism. The terminology for such occurences is
>"paraconformity", that is, something that an unbiased observer would call
>conforming, but which an evolutionist "knows" cannot be conforming because
>of the fossil contents.

    Sure, a paleontologist may suggest a paraconformity, but other
geologists will not blindly accept the interpretaton - they will test it.
    Note that a paraconformity (or any type of unconformity) does not
have to be erosive - i.e. removal of rock.  You can have a period of very
low depositional rate, or non-deposition.  This will produce a "gap" in the
rock record (non-deposition), or a "compressed" interval (very low
deposition).  Actually, there are many examples of paraconformities that
were initially recognized on the basis of fossils, and later confirmed by
detailed examination of the contact (demonstrating, for instance, subaerial
weathering of the sediments below the paraconformity); very fine
biostratigraphy (finding the missing fossils in a very thin, "compressed"
interval); or lateral tracing of the contact to demonstrate that the beds
above and below the contact do intersect in an angular unconformity, but at
a very low angle that is difficult to recognize in a single outcrop.
    A friend of mine here at the University of Calgary discovered a
2cm-thick limestone bed that contained two "missing" fossil zones in a
section of Devonian limestone in Morocco.  A significant paraconformity was
originally interpreted for the horizon.  The 2cm-thick limestone bed is now
interpreted as a "compressed" interval that fills the "gap".


4. GREEN RIVER FORMATION AND OTHER VARVES

>>   How do you explain the formation of varves?  The Green River formation
>>     in Wyoming contains 20,000,000 annual layers, or varves,
>>     identical to those being laid down today in certain lakes.
>>     [From: [e-mail] (William H. Jefferys)]

>In Whitcomb & Morris, ("The Genesis Flood"), pages 424-428 talk about the
>Green River formation. The book was written in 1961, so things may have
>changed, but it says that the only real study of the formation was made
>more than thirty years before that by Bradley, with all other papers
>pointing back to this one.

    The Green River Formation is still actively studied today.
Especially because of the economic potential of the substantial oil shale
deposits.

>They say that the 6 million years (to deposit) figure was based on
>Bradley's estimates of an ancient drainage basin's size, slope, character,
>erosibility, drainage characteristics, and the amount of water available.

    Well, of course these affect it.  So?  Is there any evidence that
the estimates Bradley made were off by, say, several orders of magnitude
(6000 versus 6 000 000)?  Or are we talking about a variation of "only" 50%
(3 000 000 years)?

>They also say that the Green River formation has layers that are too thin
>and too uniform over too wide an area to have been deposited in a normal
>lake bed.

    What an insight!  Yes, it was a _big_, _deep_ lake, not a "normal"
lake.  The Green River Formation occurs over a very large area.

>That is, there are no signs of any stirring up of the sediments or of any
>deposits that reflect flooding conditions where large amounts of sediment
>would have been dumped into the lake and would have sorted out in graded
>series.

    Man, haven't these guys heard of "proximal" versus "distal"
sedimentary environments?  Proximal is nearshore, near the sediment sources.
Distal is away from the shore, in the central, deep part of the lake, below
the influence of waves, and well away from the front of active deltas.
Think of proximal environments as "on the beach", and distal as "out to
sea".

Clearly the varves were deposited in the centre of the lake, in distal
sedimentary environments - not near shore, because the wave activity and
high sediment influx near the shore would interfere with the deposition of
the thin, continuous layers.  This still leaves a problem, since the normal
lake infauna (worms, clams, etc.) would burrow in the sediments and disturb
the varves.  However, it is not uncommon for lakes (especially large, deep
ones) to become stratified - that is, have an oxygenated, warm water layer
near the surface; and a cool, anoxic (little or no oxygen) bottom layer.
What happens to the infauna at the bottom of the lake in the anoxic layer -
it dies.  In fact, variations in the vertical position of the anoxic layer
is thought to be the reason for the massive fish kills that periodically
produced the beautiful fish fossils from the Green River Formation (they
occur in the varved sediments).  The anoxic conditions are perfect to
suppress the decay of the animals that fall into the lake, allowing them to
be preserved over thick intervals of rock.

>They have pictures of true lake deposits and of the Green River shales,
>and the difference in appearance is dramatic. From this, it seems to me
>that the Green River deposits are not what they claim... That a lake sould
>not have been so still and undisturbed form six million years that there
>is no sign in the formations.

    See above.  Their "dramatic difference" is the difference between
proximal and distal lake environments.  Note that in a small lake, all you
may see is the proximal environments, because you are always close to shore.
Morris et al. should go snorkelling in a large anoxic lake sometime.
    Besides, the Green River Formation is not just the varved shales
(which really would be anomalous).  It also contains the nearshore, more
proximal facies (rock types), including terrestrial river channels and
shallow lake deposits.  The proximal facies laterally intertongue with the
varved, distal shales, exactly as predicted.  Also as predicted, the
proximal deposits are better oxygenated, and contain bottom dwelling faunas,
like snails and clams.  You can see these deposits along the road cuts in
Spanish Fork Canyon, Utah, southeast of Salt Lake City [Rigby, J.K., 1968.
Guide to the Geology and Scenery of Spanish Fork Canyon Along U.S.  Highways
50 and 6 Through the Southern Wasatch Mountains, Utah.  Brigham Young
University, Geology Studies, v.15, part 3, p.1-31].
    A more serious problem with the short amount of time used by some
flood models is the wide lateral area of deposition.  There are millions of
individual varve layers.  It does not matter whether they are one year for
each varve, you still must make millions of laterally continuous layers by
some sort of event that takes a finite amount of time.

    The sedimentology puts some constraints on the rate.  The varves are
composed of very fine material - clay-sized organic and mineral grains -
that is graded into alternating mineral-rich and organic-rich layers.  The
water must be slow moving for the fine-grained material to settle out, and
in order to leave the underlying layers undisturbed.  Additionally, you must
spread this fine-grained layer over many hundreds of square kilometres,
allowing the minerals (more dense) to settle first, followed by the organics
(less dense).  In modern environments, such laterally continuous laminations
take months to form (at least).

    Even if you make a _ridiculous_ assumption, and say each varve could
form in a few minutes over hundreds of square kilometres, you are still
dealing with much longer than some flood creationist models propose.  How
many minutes in a year? 60X24X365=525600, i.e. about half a million.  So,
even with these _ridiculous_ assumptions, the deposition of 20 million Green
River Formation varves took almost 40 years - and this is only one of many
older and younger formations, including varved ones!!
    A good example is the mm-thick laminae of alternating, very
fine-grained calcite and anhydrite ("dehydrated" gypsum) in the Permian
Castile Formation, Texas [Anderson, R.Y., Dean, W.E., et al., 1972.  Permian
Castile varved evaporite sequence, west Texas and New Mexico.  Geological
Society of America, Bulletin, v.83, p.59-86].  Individual laminae are
traceable over tens to hundreds of kilometres.  Similar laminated carbonates
and evaporites occur in Alberta.  Producing these units by catastrophic,
rapid processes is very difficult to envision - especially evaporites
(anhydrite, gypsum, salt).
    If you start using reasonable lower limits on a varve's formation -
say, a few hours, days, or even months - the duration for the formation
becomes correspondingly much longer.  So, it does not matter if 1 varve = 1
year exactly - the total duration is still a long time.  In fact, in the
Dead Sea, one varve lamina is deposited every three or four years.  If you
restrict the deposition of all the varves to the 1 year total duration of
flood models, you must deposit a varve in a few seconds (assuming you have
all year - not taking into account other, thicker rock formations).  This
does not jive with the physics of fluid mechanics.
    This sounds very supernatural to me.

    -Andrew
    [e-mail]