7/27/2019 Fossil Forest
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Conservation cases
Fossil forests are very rare, they are trees preserved in the
original standing upright position. Such a forest
was found in Bkkbrny, Hungary in 2007. Bkkbrny is a village in
North-Hungary, situated in the
foothills of the Bkk Mountains; once it was on the shore of the
Pannon sea. "The Pannonian Sea was a
shallow ancient sea located in the area today known as the
Pannonian Plain in Central Europe. ThePannonian Sea existed during
the Miocene and Pliocene epochs. "
(http://en.wikipedia.org/wiki/Pannonian_Sea) The water level 7
millions years ago suddenly rose, drowned
also the forest near the shore. An inundation must have occurred
which permitted the abrupt sedimentation
of huge amounts of sands and consequently the preservation of
the stumps.
The forest was found in a opencast lignite mine, in 60 m depth,
only in an 50 x 100 m area. The lignite
seams extend to 10 m and are overlain by sand layers of up to 60
m formed during the Late Miocene. It is
overlain by 56 m of grey sands, which is followed by Pannonian
and Pleistocene sands, aleurites and
gravels. Sand of a prograding delta covered the landscape,
preserving the trunks in waterlogged condition.
There were discovered 16 swamp cypress (Taxodium) trunks of
Miocene age (probably Taxodiumdistichum). The trees were covered by
a sandstorm up to a height of 6 meters (from the originally 30-40
m),
and their trunks were preserved intact, without fossilization of
the wood. The find is unique in Europe, since
trees this old have never been found in their original state and
original place before.
They are 1,5-3 m large of diameters, some of them can reach 10
tons. At the moment of the waterlogging
they were about 300-400 years old. The upper part of the stumps
(from a height of ~5 m) either did not get
buried or later became exposed and was degraded.
For 7 million years oxygen-free, bacteria-free, upwards
percolating groundwater preserved the trees and
particulate organic matter. For the first sight the trees looked
like normal, but a closer observation showed
decortication and degradation by various biotic and abiotic
factors as fungi, animals, climatic factors. Living
Cupressaceae (esp. Taxodium) are known to resist wood-degrading
fungi and wood-borer insects. Despite
this, "the trunks all indicated a basally buttressed form and
showed lobed xylem in cross section . In most
cases the central (3050 cm) part of the xylem was not retained
due to heartrot. The cavity inside the
stumps was often filled with the grey sand that embedded the
stumps. The basal part of the stumps were
embedded in the underlying lignitic layers. Roots attached to
the stumps could not be recognized, possibly
these are not retained."
Stems has been permanently below groundwater level for 7 million
years. In the summer of 2007, while
excavation work progressed, trees stood in summer heat, under
direct sunlight, starting to dry, got fractured
and contracted, producing thin peels . Unfortunately in this way
we've lost 6 trees.
To understand the underwater bacterial decay the researchers
were mapping of patterns s by X-raycomputer tomography and
identified decaying agents by scanning electron microscope.
3 of them for polish proposal they tried to conserv with sugar
tincture, adding various chemicals against the
mildew and acid-formations. This will act the part of the lost
cellulose. They are exhibited under a glass-bell.
Seems that that was the best choise to conservation.
1 tree is exhibited under water, in a tank, with some windows to
look inside.
The other 6, as first step they blew out the sand from the
trunks with a compressor. After this in the spongy
tree body injected a special glue, what after drying becomes
colourless, waterproof, and as solid as the
wood. ...There the polymer, mixing with the intercellular water,
will diffuse to the surface of the fibres. The
size of the molecule will prevent polymer from getting into the
inside of the cells. Among the
macromolecules having been absorbed to the surface not only
secondary, but also primary bonds will be
http://en.wikipedia.org/wiki/Pannonian_Seahttp://en.wikipedia.org/wiki/Pannonian_Seahttp://en.wikipedia.org/wiki/Pannonian_Seahttp://en.wikipedia.org/wiki/Pannonian_Sea
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