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Re: questions about fossilized foot prints (fwd)

From:   MX%"hjarvis@ACSU.Buffalo.EDU" 29-JAN-1997 11:01:12.12
 From: UBWings Mailer <wings@ACSU.Buffalo.EDU>

 > Questions?
 > How long does it takes to be fossillized a human footprint?

Footprints do not fossilize in the same was as bones.

Essentially a footprint is "fossilized" as soon as the layer it is
in is covered by another layer of different texture.  This can be due
to something as simple as a single flood at the right time.
 > Is it possible to determine the longevity of the soil where the
 > footprints are located?
I am not sure what the question here is intended to be.

Is it: how long can soils last?

The answer is for hundreds of millions of years, if not billions
of years.  I know of soils from as far back as the early Paleozoic,
and there may well be Proterozoic fossil soils.

Any book or article by Retallack is a good source for information on
fossil soils. He is probably the #1 expert on that subject today.

If the question means: how can one determine the age of a particular
soil containing footprints?

There are many methods which can be used in different situations.
Which one or ones are used depends on the exact circumstances. For
more recent soils carbon dating of included organic matter can be
used to date a soil.  For older soils, there are methods like fission
track and thermoluminescence and stratigraphic correlation (the most
common).  If the soil contains volcanic ash, that can be dated using
Argon-Argon or some similar long-term radioactive dating method.

 > Where have you found this human fossil footprints?
They have been found in many places, from Laetoli to North America.
 > -o-
 > We have all these questions, because we found a pathway with multiples
 > fossillised footprints in Chiapas Mexico.

You need to be careful in identifying footprints as humans.
There are many ways to be confused by prints or print-like
structures.  For instance, bears have very similar footprints
to those of humans.

You need to check for toes (unless there is good evidence of mocasins
or other footwear).  Even more important, do the prints show the
arched instep of a human foot? Any print lacking an arched instep
is probably NOT human.

swf@elsegundoca.ncr.com         sarima@ix.netcom.com

The peace of God be with you.