Last Monday (2nd February) it was World Wetlands Day, and
consequently my Twitter feed was full of stunning photographs of different
types of wetland. Much was made of their role in alleviating flooding by acting
as giant natural sponges which soak up water, as well as their biodiversity
value and ability to store vast amounts of carbon. But despite all the wetland
appreciation that I witnessed on Monday, there was very little mention of their
importance to archaeologists and palaeoecologists.
Wetlands have a whole archaeological sub-discipline devoted to them.
Wetland archaeologists are drawn to these damp, muddy environments because the
waterlogged, anaerobic conditions inhibit microbial activity and often result
in exceptional preservation of artefacts made from organic materials such as
plant fibres, hair, wood and leather. These artefacts rarely survive on dryland
sites, meaning that wetlands often preserve an additional level of detail
relating to the everyday lives of our ancestors. Wetland archaeological
sites also preserve plant and insect remains, which give us insights into the
function and economy of the sites. Additionally, wetlands contain an archive of
information relating to their own environmental history. Past changes in vegetation
can be reconstructed from pollen grains, and the remains of single-celled
organisms called testate amoebae provide information about past climates.
Wetlands were also important to people in the past. Across north-west
Europe, deposits of precious metalwork were made in both wetland and dryland
environments during the Bronze and Iron Ages. Artefacts deposited on dryland
tend to be interpreted as valuables that were either lost or hidden with the
intention of retrieving them in the future. Given that it would have been
difficult to retrieve items from wetlands once they had been deposited, these
objects are commonly thought to be votive offerings. In the past wetlands may
have been viewed as wilderness and as being resistant to domestication, and it
may be that these deposits represent an attempt to appease supernatural powers
associated with these environments during times of perceptible environmental
change. There is considerable palaeoenvironmental evidence for a shift to a
wetter climate during the Bronze Age, particularly in upland regions of
Britain. Deposition of valuable metalwork was perhaps an attempt to domesticate
and control the changing landscape during this period of wetter climatic
conditions.
To date, evaluation of this hypothesis has been hampered by a lack of palaeoenvironmental
data relating to the findspots of votive deposits - and in many cases, the exact locations of the finds are not recorded. In Orkney in 2006, when
I had just begun my PhD research with the aim of reconstructing Bronze Age vegetation
and environmental conditions in the islands, peat cutters at Hobbister in
Orphir uncovered a beautiful example of a late Bronze Age socketed axehead. Was it a votive deposit, and was there any palaeoenvironmental evidence
for changing conditions at the time of deposition? An archaeological survey of
the site had revealed various structures interpreted as the remains of a prehistoric
field system, as well as several probable Bronze Age burial mounds. The
discovery of a potential Bronze Age landscape buried by peat meant that the site
would be useful for my PhD research, even if it turned out that I wasn’t able
to say much about possible reasons for the axehead deposit.
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| Blanket bog at Hobbister, Orkney |
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| Commercial peat extraction at Hobbister, Orkney |
I analysed two peat cores from the site – one from the deepest area of
deposits to ensure the fullest possible record was recovered, and one from as
close as possible to where the axe was found. Analysis of the peats revealed
evidence for a mixed economy based on arable cultivation and livestock rearing.
The field system probably formed part of an ‘infield-outfield’ system, where fields
nearest to a settlement (‘infields’) were cultivated more or less continuously by
adding fertiliser in the form of dung, turf and seaweed, while those beyond
(‘outfields’) were only cultivated on a temporary basis, being manured only
through the folding of livestock in the summer prior to cultivation. Beyond the
outfields would have been common pasture for livestock grazing. At Hobbister
the pollen evidence indicates that this would have largely consisted of
heathland, and there is evidence from charcoal contained within the peat that
this was managed by burning to improve the quality of the grazing by encouraging
dense growth of new shoots of heather, which contain more nutrients than
old-growth heather, and by allowing grasses to grow in the gaps created by
fire.
The remains of plants preserved in the peat at Hobbister suggest that the surface of the bog became slightly wetter during the later Bronze Age, at around 1200-800 BC. If the bog became wetter at this time, it is likely that the surrounding area did too. The suitability of land for farming would have been highly dependent on local hydrology, and increased wetness may have rendered the soil incapable of supporting cereal crops. Although the pollen evidence suggests that cereal cultivation at Hobbister continued at least until the Iron Age, local people would have been extremely aware of the gradual encroachment of peat onto formerly more productive land, and it is distinctly possible that they tried to halt these changes through votive deposition.
Distinctions have been drawn between votive deposits made in different types of wetland, with the suggestion that rivers, with their opposing banks, may have been viewed as boundaries dividing communities, and that deposition here might have been a display of power and prestige to other social groups. Bogs, on the other hand, may have been the focus for ritual acts aimed at reinforcing social cohesion within communities (Fontijn 2002; Mullin 2012). Orkney has no major river systems, but the highly indented coastline may have played a similar role in dividing communities here. Hence the deposition of the Hobbister axe could be seen as an attempt by local people to maintain community integrity during a time of perceptible environmental change.
In summary, wetlands are awesome - they preserve so much information about our past that simply doesn't survive on dryland archaeological sites. Next year on World Wetlands Day, we palaeoecologists and archaeologists need to get in on the act and promote the value of wetlands for understanding our heritage!
References:
Fontijn, D.R. (2002) Sacrificial landscapes: cultural biographies of persons, objects and ‘natural’ places in the Bronze Age of the southern Netherlands, c. 2300-600 BC. Analecta Praehistorica Leidensia 33/34: 1-392 (download for free here)
Farrell, M. (in press 2014) Later prehistoric vegetation dynamics and Bronze Age agriculture at Hobbister, Orkney, Scotland. Vegetation History and Archaeobotany. doi: 10.1007/s00334-014-0507-6
The remains of plants preserved in the peat at Hobbister suggest that the surface of the bog became slightly wetter during the later Bronze Age, at around 1200-800 BC. If the bog became wetter at this time, it is likely that the surrounding area did too. The suitability of land for farming would have been highly dependent on local hydrology, and increased wetness may have rendered the soil incapable of supporting cereal crops. Although the pollen evidence suggests that cereal cultivation at Hobbister continued at least until the Iron Age, local people would have been extremely aware of the gradual encroachment of peat onto formerly more productive land, and it is distinctly possible that they tried to halt these changes through votive deposition.
Distinctions have been drawn between votive deposits made in different types of wetland, with the suggestion that rivers, with their opposing banks, may have been viewed as boundaries dividing communities, and that deposition here might have been a display of power and prestige to other social groups. Bogs, on the other hand, may have been the focus for ritual acts aimed at reinforcing social cohesion within communities (Fontijn 2002; Mullin 2012). Orkney has no major river systems, but the highly indented coastline may have played a similar role in dividing communities here. Hence the deposition of the Hobbister axe could be seen as an attempt by local people to maintain community integrity during a time of perceptible environmental change.
In summary, wetlands are awesome - they preserve so much information about our past that simply doesn't survive on dryland archaeological sites. Next year on World Wetlands Day, we palaeoecologists and archaeologists need to get in on the act and promote the value of wetlands for understanding our heritage!
References:
Fontijn, D.R. (2002) Sacrificial landscapes: cultural biographies of persons, objects and ‘natural’ places in the Bronze Age of the southern Netherlands, c. 2300-600 BC. Analecta Praehistorica Leidensia 33/34: 1-392 (download for free here)
Mullin, D. (2012) The river has never divided us: Bronze Age metalwork
deposition in western Britain. Oxford Journal
of Archaeology 31: 47-57
This post is based on my recent paper, available here:
Farrell, M. (in press 2014) Later prehistoric vegetation dynamics and Bronze Age agriculture at Hobbister, Orkney, Scotland. Vegetation History and Archaeobotany. doi: 10.1007/s00334-014-0507-6
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