Bog detective: working out the story
of Greenhead Moss
There are three main stages involved in
the pollen detective work that tells us about
Greenhead Moss, how it formed and how things changed
and developed over the last 10000 years.
1.Fieldwork
First you need to find and sample the
right part of the bog. Many lowland bogs are
surrounded by houses or agriculture and have been
affected by years of human activity. At Greenhead
Moss, peat has been cut for fuel since at least the
nineteenth century, when the rides (raised banks of
peat) and drains were put in. More recently,
open-cast mining has taken out a large chunk of peat
from the south of the moss, right down to the
underlying rock.
So before research into the palaeoecology
or past ecology of the moss could start, we had to
work out where the bog might be less disturbed, to
make sure we wouldn’t miss any parts of the peat
record of the past environment. We did this by
looking at plans of the moss and by looking at the sediment
stratigraphy - changes in the plants that make up
the peat from the bedrock, more than 4 metres below
our feet, up to the surface. This helped us decide
which was the best place to sample.
From this we know that the rides provide
the fullest, least disturbed peat record and we chose
to sample near the south-western corner of the moss.
This area has always been near the edge of the bog,
so the pollen from there will tell us about
vegetation on the bog (the wetland) and plants
growing on the dryland next to it, where people would
have been most active.
To study the full record preserved in
the peat, you have to remove a peat core which
includes the top peat beneath your feet, right down
to the bedrock, more than 4 metres below. There are
different ways of sampling the peat. We used a Russian
peat corer, which is 1 metre long.
What does a
Russian corer look like and how does it work?:
www.shef.ac.uk/~ap/pollen/coring.html
1. First we
push it into the peat with rods that fit onto the top
of the corer.
2. Then we turn
the rods, which move the sampling chamber around
while the fin on the long side holds it in the peat.
3. This cuts a
1 metre long, semicircular peat sample and holds it
in the chamber.
4. We pull it
out and wrap it up to take back to the laboratory.
5. This is
repeated until we have sampled all the way through
the peat, each core taken from further down into the
peat.
A Russian corer which
has just been opened to reveal the peat core from
which pollen will be extracted in the laboratory.
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