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Friday, 15 May 2009

Tunguska Questions

Tunguska Questions

Paul bristolia at
Fri May 15 14:26:27 EDT 2009

In regard to Tunguska and bioturbation, Meteorites USA asked:

“Paul H's post on bioturbation brings up an interesting
question. The first expedition led by Leonid Kulik to
Tunguska in 1927 to study the devastation and search
for meteorites happened 19 years AFTER the event
in 1908, (He had an earlier expedition in 1921 but
wasn't successful in reaching the epicenter until 1927).

19 years is a LONG time for meteorites in the forested
and swampy environment full of little critters, insects,
and plants that could bury any stones. How deep can
meteorites be buried in 19 years of snow, rain storms,
mudslides, spring melt, critters, ants, termites, and
other animals?

This is very interesting point, because 19 years likely would
be sufficient time for relatively small fragments of meteorite
to be buried. Dr. Donald Johnson found right after buying the
in which he lives, a layer of bricks buried beneath 2 or 3 inches
of soil. This had been bricks that had been placed on the
ground, without using any mortar hold them together, as
simple patio. Given when the house was built, the bricks
could not have been placed on the ground more than 20
years before he found them. It was this discovery that
inspired him to start his research on bioturbation from what
can remember of his class lectures.

The depth of burial at Tunguska, would depend, in part, on
how deep any permafrost present at that location melts each
year and how deep that and other processes allow bioturbation
to occur. I suspect that between bioturbation and cryturbation,
any small and even relatively large, meteorite fragment would
very quickly disappear beneath the soil and muck.

It would be interesting to find some specific information about
the soils present at the Tunguska Site and do a detailed taphonomic
analysis of what the soil and sediment data means in terms of
"meteorite taphonomy". It would be no different then doing an
analysis of site formation processes for an archaeological survey
area in order to either predict where the archaeologists should
look for artifacts or in order to interpret what was or was not
found by the archaeologists when they surveyed an area.

I have done enough site formation processes analyses for archaeologists,
that I could, for a scientific search for meteorites, do the same thing for
a strewn field and make a prediction of where a person would expect
meteorites to be found.

Best Regards,

Paul H.

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