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Crannogs
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Many Scottish
lochs are littered with small, tree-filled islands, poking their
heads up just above the waterline. What most people don't realise
is that they are often man-made islands, and once contained spectacualr
Iron Age dwellings. Thatched, timber roundhouses were supported
on huge, wooden piles driven deep into the bed of the loch. The
surrounding water was the inhabitants' defence.
The
Oakbank Crannog - Loch Tay - Factsheet
- Since
1980 archaeologists have explored the waters
of Loch Tay for crannogs and have excavated
one at Oakbank, just off the village of Fearnan.
It was a remarkable discovery. Preserved in
the loch's cold, peaty waters were structural
timbers, food, utensils and 2600 year old
clothing. They even discovered a butter dish
with butter still clinging to the inside of
it - a bit past its sell-by date though.
- In
1994 experimental archaeologists from the
Scottish Trust for Underwater Archaeology
began to discover the secrets of the Iron
Age crannog builders when they set about reconstructing
a crannog on Loch Tay using exactly the same
material as the original at Oakbank.
- The
reconstruction at Kenmore involved building
a thatched roundhouse on a timber platform
15m across, which was connected to the shore
by a timber causeway 20m long. The whole structure
is supported on 168 timber piles.
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Timber was obviously the most important building
material for the crannog builders. To provide
all the varieties of timber required, the
Iron Age farmers must have carefully managed
their woodlands. They would have been skilled
woodworkers and would have understood the
differing properties of tree species for everything
from structural supports to making cooking
bowls.
- How
Were Crannogs Constructed?
To begin with rafts and boats must have been
used, as well as wooden scaffolding built
out in the loch. The first stage was to create
an artificial island out of timber piles.
Alder trees, 8-10m long, were used for the
piles. Buoyant on water, the alder piles would
have been easy to manoeuvre on the water's
surface but very difficult and tiresome to
pull vertical.
- Iron
Age Pile Driving
One of the most challenging tasks the archaeologists
faced was how to drive the alder piles up
to 2m into the lochbed using only Iron Age
technology.
A crosspole would have been lashed to the upright pile and twisted
back and forth to create enough momentum to drive it two metres
into the loch bed.
It has been estimated that it would have taken 12 days for the
Iron Age builders to erect and secure the 168 piles needed.
Once
the piles were driven, the platform and roundhouse of the crannog
could be jointed, pegged and lashed onto the structure. Round
timber poles were used for the flooring and to form the structure
of the roundhouse. Its roof was thatched with reeds from the
loch, with its enclosing walls made from hundreds of flexible
hazel stems woven together.
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