2.
Laboratory analysis
The first stage in the lab is to
describe the peat: the sediment stratigraphy.
Information on what the peat looks like and what
plants are preserved from the surface down to the
base of the core really tells us about changes in the
environment on the bog through time. Different
environments produce characteristic sediments because
the conditions and plants in each
environment were different, so we can tell the
difference between lakes, fens and bogs by looking at
the sediments.
A peat sequence
exposed by open-cast mining on Greenhead Moss:
changes in the stratigraphy are easily visible.
The next step is to take peat samples
and get the pollen out of them to see what plants
were growing in the area at different times in the
past.
1. We take
small samples of peat at regular intervals, from the
base to the top of the core, and put each peat sample
in a test tube.
2. All the
samples are treated with chemicals and sieved to
break up and remove any mineral grains and the
organic peat that the pollen is preserved in. Because
the walls of pollen grains are resistant to
chemicals, they survive this treatment and so
finally, they are all that is left in the test tubes.
3. The pollen
is then stained, to make the wall structure easier to
see under the microscope.
4. All the
water is removed from the pollen grains and they are
transferred to small glass vials with silicone oil to
preserve them.
5. A small
amount of each pollen sample in silicone oil is then
used to make slides which are looked at with a
microscope. Palynologists view each slide
systematically, identifying and counting each pollen
grain seen. Fragments of charcoal are also
measured and recorded to tell us about burning and
changes in the fire regime.
6.
Finally, when all the samples have been counted like
this, the results are put together to create a pollen
diagram and this is what tells us the story of
the bog and the surrounding landscape.
Extarcting and analysing pollen
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