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Professors Ogden and Palmer
are hoping
that the results from this site, as well as several other sites
in Northland, may
hold the key to understanding the environmental history
of this region as well as future long term global
weather patterns.
Dr
Ogden has concluded, from carbon dating techniques, that the age of the
timber in this hole is around 46,000 years old. Therefore, the study of this
timber, the surrounding soil samples and pollen samples (collected and
analysed by Donna Costas - pictured) provide information about the climate
46,000 years ago. Other sites yield information relating to other periods in
our past. Gradually a larger picture of our climatic history is being
assembled. Information has also been gathered from a second forest on this
site, buried beneath the first forest. It's age is estimated to be 100,000
-150,000 years old using M.O.I.S. testing methods but this is still not
conclusive. |
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A study of the peat and sand around the timber
leads to a theory about the fate of these trees.
Dr Ogden and Dr Palmer believe that in many cases
the kauri forests have been preserved by natural changes in
climatic conditions. They theorise that the trees grew around 44,000 BC in the
period before the last Ice Age, when conditions were colder (2 degrees
Celsius cooler) and a lot wetter than is the case at present. As
temperatures rose so did sea levels and ground water levels and
swamps began to form.
The trees grew in or around the peat swamp
and fell in and died as the swamps expanded. As it became colder still (perhaps 5 degrees
cooler than at present) and drier and windier than during the last Glacial
Maximum, peat ceased to form and the swamp was covered by drifting sand
dunes. This can be seen on the sides of the hole. The dark peat can be seen
at the bottom with the sand layer covering it. The timber straddles the two
layers. |
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When sea levels fell again as the temperature
became cooler the swamps were turned to bogs and the lack of
oxygen and flowing water coupled with the chemical makeup of the
peat soil preserved the kauri timber.
In time, sand drifted over the area.
Once temperatures began to rise again the whole process repeated,
preserving subsequent forests.
Of particular interest is that the extrapolation of the data
predicts a reasonably rapid fall in the average temperature over
the next 25,000 years, even without taking into account any
effects from Global warming. |
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