[asa] Turkey’s Lake Van -500,000 Years History Stored Year By Year

From: Janice Matchett <janmatch@earthlink.net>
Date: Wed Mar 14 2007 - 21:43:10 EDT

Two items of possible interest. ~ Janice :)

[1] Video 3/14/07 Click here
http://www.foxnews.com/video/index.html and
scroll down to the "Shows" catagory then click on
the Chris Horner video clip entitled Inconvenient Truth?
 Is AlGore cashing in on carbon credit scheme?
Chris Horner
Bio: http://www.freerepublic.com/focus/f-news/1785268/posts?page=38#38

[2] 500,000 Years Of Climate History Stored Year By Year
Alpha Galileo ^ | 3-14-2007
Posted on 03/14/2007 8:58:04 PM EDT by blam
http://www.freerepublic.com/focus/f-news/1801012/posts [refresh browser]

The bottom of Turkey’s Lake Van is covered by a
layer of mud several hundreds of metres deep. For
climatologists this unprepossessing slime is
worth its weight in gold: summer by summer pollen
has been deposited from times long past. From it
they can detect right down to a specific year
what climatic conditions prevailed at the time of
the Neanderthals, for example. These archives may
go back as much as half a million years. An
international team of researchers headed by the
University of Bonn now wants to tap this
treasure. Preliminary investigations have been a
complete success: the researchers were able to
prove that the climate has occasionally changed
quite suddenly – sometimes within ten or twenty years.

Every summer an inch-thick layer of lime –
calcium carbonate – trickles down to find its
final resting place at the bottom of Lake Van.
Day by day during this period millions and
millions of pollen grains float down to the
depths. Together with lime they form a
light-coloured layer of sediment, what is known as the summer sediment.

In winter the continual ‘snowdrift’ beneath the
surface changes its colour: now clay is the main
ingredient in the sediment, which is deposited as
a dark brown winter sediment on top of the
pollen-lime mix. At a depth of 400 metres no
storm or waves disturb this process. These
‘annual rings’ in the sediment can be traced back
for hundreds of thousands of years. ‘In some
places the layer of sediment is up to 400 metres
thick,’ the Bonn palaeontologist Professor Thomas
Litt explains. ‘There are about 20,000 annual
strata to every 10 metres,’ he calculates. ‘We
presume that the bottom of Lake Van stores the
climate history of the last 800,000 years – an
incomparable treasure house of data which we want
to tap for at least the last 500,000 years.’

250 metres of sediment = 500,000 years’ worth of climate archives

Professor Litt is the spokesman of an
international consortium of scientists that wants
to get stuck into a thorny problem: using high
tech equipment they want to cut drill cores as
thick as a man’s arm out of the lakebed sediment
from a big floating platform – not an easy task
at depths of 380 metres. The researchers want to
drill down to a sediment depth of 250 metres. For
this they have applied for funding by the
International Continental Drilling Programme
(ICDP). This would be the first time that an ICDP
drilling was headed by a German. The prospects of
this happening are not bad. A preliminary
application was assessed as very good by the ICDP
Executive Committee – above all thanks to a
successful preliminary investigation which the
researchers had carried out at Lake Van in 2004.
The German Research Council (Deutsche
Forschungsgemeinschaft, DFG) financed this. It
has just extended the project for two more years.

The sediment promises to deliver a host of
exciting results. For example vulcanologists can
determine exactly when volcanoes near the lake
erupted. In this case there will suddenly be a
black layer of ash between the annual layers.
‘With our test drill we counted 15 outbreaks in
the past 20,000 years,’ Prof. Litt says. ‘The
composition of the ash even reveals which nearby volcano it originates from.’

Chubby-cheeked pollen

Even earthquakes in this area of high geological
activity are painstakingly stored in these
archives. What is the most interesting aspect for
Thomas Litt, however, is the biological filling
contained in the summer layers, especially. The
microscopically small pollen tells the
palaeobotanist what sorts of things used to
flourish on the shores of the lake. In a piece of
sediment the size of a sugar cube up to 200,000
grains of pollen can be trapped. Under the
microscope the fine dust reveals a very special
kind of beauty. The pollen of yarrow is as
prickly as a hedgehog, the pollen of pine with
its air sacs resembles the chubby-cheeked face of
a hamster, ‘and look at the olive tree,’
Professor Litt enthuses, ‘it’s also got a very nice pollen grain.’

The researcher normally recognises at once what
genus or species the finds belong to – even when
they are several thousands of years old, since
the exine, the outer coat of the grain,
successfully resists the ravages of time. ‘The
material is extremely resistant to environmental
influences and even withstands strong acids or
bases,’ Professor Litt explains. Using
hydrofluoric acid or potassium hydroxide he
dissolves the pollen grains from the sediment
samples; the grains prove to be completely
impervious to such rough treatment. Under the
microscope the botanists then assess how much
pollen of which species is present in the layer
in question. ‘At interesting points we take every
centimetre of material from the drill cores; in
this way we achieve a chronological resolution of a few years.’

The pollen permits pretty precise statements to
be made about temperature and average amount of
precipitation for the period covered by the
finds, as every species makes different demands
on its environment. ‘If we find pollen in a
specimen from different species, whose demands on
its habitat are known, we can make a plausibility
statement about the nature of the climate of the
time,’ he adds. ‘Lake Van promises to provide
unique insights into the development of the
climate in Eurasia – and thus for assessing the current warm period.’

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Received on Wed Mar 14 21:43:32 2007

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