Re: fossilization rate

From: Steven M. Smith (smsmith@helios.cr.usgs.gov)
Date: Fri Jan 21 2000 - 14:00:06 EST

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    At 03:10 PM 1/21/00 +0900, Wayne Dawson wrote:
    >I remember reading that that YEC insists that fossilization can occur
    >"within 100 years". It seems a little toooooooo fast. What exactly
    >do they mean by "fossilization" in this context.
    >
    >Is this in reference to bone and other calcium based materials, as
    >opposed to say cartilage or other even softer materials?
    >
    >Would that correspond to the most "ideal" imagined conditions
    >(essentially only possible in a laboratory)?
    >
    >Are there any real facts at all behind this claim?

    I have never measured fossilization rates, however, I would like to
    make a few observations on this line of reasoning concerning
    fossilization.

    Asking how long it takes for fossilization to occur is analogous to
    asking how long it takes to go from New York to San Francisco. The
    answer is that it depends entirely upon the route and process that is
    used to get there. You could get there in a few hours on a non-stop
    flight. Or you could spend months or even years if you choose to go
    by a slower method or indirect route (a sailboat journey around Africa
    with many lengthy stops at various ports comes to mind.)
    Alternatively, if you go by automobile, stop for a few days in Kansas
    City, meet a girl, fall in love, get married, and so on ..., you may
    never get to San Francisco. The same scenarios are possible for
    fossilization rates -- except that in this analogy we have a goal to
    reach San Francisco while fossilization is not a goal but simply a
    fortunate consequence of the circumstances.

    For example, let's talk about fossil wood. I have found fossil wood
    molds in volcanic ashflows that were formed almost instantaneously.
    However, none of the wood survived, all that is left is the hollow
    mold. In one location I came upon, the molds were filled later with
    silica to form casts of the original pieces of wood. This example,
    however, may not address your concern since I perceive that the actual
    topic of concern by YEC advocates is the "petrifaction" rates (i.e.
    the replacement of organic matter by inorganic matter while preserving
    some internal structure of the original object.)

    Under ideal conditions, petrifaction can also apparently take place
    quite rapidly. Such circumstances would include:

            (1) a piece of highly porous wood falling into a hot spring
    which is supersaturated with respect to silica, lime, or iron. (In
    iron springs, I have seen red, iron-hydroxide crusts deposited on and
    potentially beginning to replace wood from trailing branches of live
    trees.) Under perfect conditions, I suspect that petrifaction could
    potentially begin to occur within days or weeks.

            (2) wood that is quickly buried by porous volcanic ashflows
    and ash falls (at temperatures below the flash point of wood) and
    subjected to percolating, warm, silica-saturated ground waters. I
    suspect that petrifaction could begin within a few decades. (It would
    be interesting to take some samples of wood buried by various recent
    volcanic events, including Mt. St. Helens, and determine their degree
    of petrifaction.)

    However, very little of the earth's surface is covered by volcanic ash
    deposits or supersaturated mineral springs. Most wood rots before it
    can be preserved. Occasionally it can be preserved unmineralized for
    long periods of time provided that it is protected from agents of
    decay. In areas affected by glaciers of the Ice Ages (the Great Lake
    States of the U.S.), I have seen well preserved but unmineralized wood
    (and bone) in anaerobic peat and muck deposits. These often begin to
    rot within days of being exposed to air. Yesterday, I saw a piece of
    wood that had been found protruding from a retreating mountain glacier
    in northern Washington state. It appeared as fresh as well-seasoned
    firewood yet had been radiocarbon-dated at 5000 yrs B.P. (A date that
    even most YEC's would not greatly dispute.) There is little doubt
    that wood can be preserved without petrifaction for thousands of years.

    Here in Denver, we have a lot of petrified wood eroding from
    sandstones that are about 50 to 60 million years old (as dated by
    radiometric methods on interlayered lava flows). Recently a housing
    subdivision was built on a site where I had previously found petrified
    wood. The petrified wood was almost always in small pieces and
    although it was rather drab in appearance, contained finely fossilized
    wood structures. As construction began, more and more wood fossils
    were exposed. It soon became evident that the pieces of well
    petrified wood were simply discontinuous fragments from within largely
    un-petrified logs. The petrifaction process had been very "spotty"
    and only a minor amount of the fossil wood was actually replaced.
    Much of the wood was carbonized (like coal) and some fragments were
    still very woody. Except for the few silica-petrified pieces, all of
    this fossil wood exposed by the construction process disintegrated
    within days of being exposed.

    I realize that hauling out examples of "60-million-year-old"
    non-petrified wood fossils will not convince any YEC advocates of a
    great age to the earth since it begs the question. Nevertheless, this
    last site greatly impressed upon me the enormous variability of
    petrifaction rates. IMO, the degree of petrifaction, BY ITSELF, is
    neither a good argument for nor against the age of the earth - it is
    irrelevant. Unless we have evidence to inform us of the route and
    process by which petrifaction took place, we can say very little about
    how long it took to get to San Francisco. I haven't made it to San
    Francisco yet -- in either sense of the metaphor.

    Steve
    [Disclaimer: The opinions expressed here are my own
    and are not to be attributed to my employer.]

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     Steven M. Smith, Geologist Office: (303)236-1192
     U.S. Geological Survey Fax: (303)236-3200
     Box 25046, M.S. 973, DFC smsmith@helios.cr.usgs.gov
     Denver, CO 80225
     --The USGS National Geochemical Database NURE HSSR Data Web Site--
      http://greenwood.cr.usgs.gov/pub/open-file-reports/ofr-97-0492/
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