Reconstructing Bronze Age environments at Hobbister, Orkney

by Michelle Farrell (@DrM_Farrell)

Last Monday (2^nd 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.

 

Blanket bog at Hobbister, Orkney

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)

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

How do you get to be a palaeoecologist?

Researcher profile: Dr Michelle Farrell (@DrM_Farrell)


As discussed by several GEESologists in our series of researcher profile blogs, it took me a long time to realise that what I do for a living now could actually be a real job! Even while I was an undergraduate student, it never occurred to me that several of the staff members in my department (postdocs, postgraduate students etc) were paid mainly to carry out research, and that research also formed a significant part of my lecturers' jobs. A career in academia was something that I knew very little about until I accidentally fell into one, and now I find it hard to contemplate doing anything else - I am incredibly lucky to have a job that I find so interesting.

I'd always been interested in natural history from an early age, mainly stimulated by childhood holidays in the UK and France. I grew up around two hours drive from the Lake District and Yorkshire Dales, and hiking with family and friends in these regions convinced me that I wanted to pursue a career that involved working outdoors. During a career-planning session at school we had to complete a computer-based questionnaire, which used our answers to come up with a list of suitable jobs. From this, one job that struck me as interesting was a national park ranger (some of the other options were a little less desirable, 'waste management operative' being one that has stuck with me over the years). I loved the idea of being able to work in one of the national parks that I enjoyed spending so much of my leisure time in, and wanted to help conserve it for future generations. With this in mind I went off to the University of Wales, Aberystwyth to study for a BSc in Environmental Science.

Growing up in the 1990s, when issues such as acid rain, the ozone hole and global warming were front-page news, I was looking forward to learning more about the effects that people were having on the environment during my degree studies. However during some of my introductory lectures at Aberystwyth, I discovered that people had actually been affecting the environment for thousands of years already, and that it was actually possible to study these past impacts. I became particularly interested in palaeoecology, though I never imagined that I would actually be able to pursue a career in this field. Circumstances prevented me from undertaking a palaeoecological dissertation in my final year, and I made do with an ecological one instead, still planning to follow a career in ecology and/or conservation.

When I began to search for jobs towards the end of my degree, I discovered that vast amounts of practical experience were required even for an entry-level ecology or conservation job. I had done some voluntary conservation work with the Aberystwyth Conservation Volunteers, and my degree had equipped me with some practical ecological skills, but it wasn't enough. Several months' unpaid voluntary work was needed to allow me to gain the necessary skills. Student maintenance grants had been abolished the year before I began my degree, and with a fairly hefty student loan to pay off I needed to find paid work. I took a job in sales, and while I learned some valuable people skills and gained a lot of administrative experience (both of which are very useful in my current role!), I soon knew that it wasn't what I wanted to do forever.

When a friend forwarded me a job advertisement for a research assistant at the Wetland Archaeology and Environments Research Centre (WAERC) at the University of Hull, I realised that the thing I'd found really interesting at university could actually be a job! I didn't have any practical experience, but as the advert said that training would be provided for the right candidate, I figured it was worth a try. Unsurprisingly, I wasn't shortlisted for interview, but Jane Bunting wrote to me and suggested that I apply for one of the funded PhD studentships that the Department of Geography were currently offering. Until then I had no idea that you could be paid to do a PhD, so I jumped at the chance. I had no access to an academic library, so Jane sent me a few key papers in the post, I put together a project proposal, and I was invited for interview and offered a studentship.

I moved to Hull to start my PhD in September 2005 and have been here ever since! My PhD used pollen analysis and a suite of allied techniques to explore concepts of marginality and the response of human populations to changing environmental conditions in prehistoric Orkney. I became very interested in integrating palaeoenvironmental and archaeological data, and was keen to work more closely with archaeologists on future projects. Archaeology was also something that I'd always been interested in, but despite being a big fan of Time Team, I hadn't even realised it was something you could study at university, let alone that it could be a job! 

Pretending to hold up one of the standing stones at Carnac on a family holiday to Brittany: apparently my interests in archaeology also began at an early age, though I didn't realise this until much later...

Hugging the Stone of Setter on Eday, Orkney during fieldwork in 2006: nothing much changes...

After defending my thesis, I continued to work with Jane as a post-doctoral research associate on the Crackles Bequest Project, which I'm sure will feature in future blog posts from one or both of us. During 2012 and 2013 I worked part-time on this project, as I was also working as a palaeoecologist for English Heritage as part of their Environmental Studies Team based at Fort Cumberland in Portsmouth. This gave me plenty of opportunities to work with archaeologists, and it was through contacts that I made here that I ended up working on my current project - producing pollen-based reconstructions of past land cover in some iconic Neolithic landscapes as part of the Times of Their Lives project run by Cardiff University and English Heritage. This will be the final project that I work on as a GEESologist at Hull - on May 1st I start work as a research fellow at Queen's University, Belfast, and will be working with archaeologists and other palaeoecologists on the FRAGSUS project, which is examining human-environment relationships in the island environment of Malta. This will be a big change after 8.5 years in Hull, but it's a challenge that I'm looking forward to and it's hopefully one more step along the path to the coveted permanent academic job!

I feel incredibly fortunate to have figured out how to be a palaeoecologist - it's challenging, much more interesting than most other jobs I can think of, and good fun too - I've been on some fantastic fieldwork at locations all over Europe and have met many great friends and colleagues along the way. My advice to anyone who is fascinated by a particular topic at university but can't imagine how it could ever lead to a career - ask your lecturer about it, you never know!

Seeing the wood for the trees in Neolithic Orkney

by Michelle Farrell (@DrM_Farrell)

As I mentioned in my first GEES-ology blog post, palynology can be applied, along with a whole host of other scientific techniques, to help answer archaeological questions. One of my main research interests lies in understanding how people interacted with their environments during prehistoric times – not just the ways in which human activities may have impacted upon the environment, but also the effects that environmental conditions may have had on the development of human culture and society. I am particularly interested in how these human-environment relationships may have differed in areas that are currently perceived to be marginal for human settlement, and especially in island environments where finite natural resources would have been available.

To date, my research in this field has focused on the islands of Orkney, situated about 10 km off the northern coast of Scotland. This apparently open, hyper-oceanic environment would presumably have provided quite marginal conditions for human settlement, yet Neolithic communities flourished and the islands contain some of the most spectacular remains of this period in north-west Europe. The importance of these monuments is reflected by the designation of the Heart of Neolithic Orkney World Heritage Site, which includes the settlement of Skara Brae, the chambered tomb of Maeshowe, and the ceremonial sites of the Stones of Stenness and the Ring of Brodgar.



One of the houses at the Neolithic village of Skara Brae,
occupied between about 3200 and 2500 BC

The Stones of Stenness in west Mainland



Berriedale Wood in northern Hoy: Britain's most northerly natural woodland,
and the only patch of native woodland surviving in Orkney today

It has generally been argued that the Neolithic structures of Orkney have survived so well because they were built in stone - the use of stone for construction seems to have been rare elsewhere in Britain at this time. Orkney today is largely treeless – in fact the only natural woodland to be found on the islands is that at Berriedale in northern Hoy, which actually represents the most northerly natural woodland in the British Isles. There is a long-held assumption that Orkney has been devoid of substantial woodland throughout much of the Holocene (the period of time since the end of the last ice age, approximately 11,500 years ago, to the present day). Was the use of stone for construction in Neolithic Orkney therefore an environmental necessity?



Yesnaby in west Mainland serves to demonstrate why the islanders
might have preferred to use flagstone for construction even if plenty of
timber was available! The flagstone easily breaks off along the
bedding planes in perfect, evenly sized slabs ready for building.

Palynological investigations carried out in the 1960s and 70s suggest that Orkney did once have quite extensive tree cover, although high percentages of birch and hazel pollen have led this to be dismissed as ‘scrub’ or ‘shrubland’ rather than true woodland. These studies have often been used to provide context for the Orcadian archaeological record, the story being that the islands were covered with birch-hazel ‘scrub’ during the earlier part of the Holocene, which was then almost entirely cleared for agriculture around 5500 years ago. This apparently forced the islanders to the readily available Orcadian flagstone for their construction materials.

Many of these early palaeoecological studies were hampered by poor dating of the sequences investigated, and when I plotted the dates of woodland decline from previous reliably dated studies, along with dates from new cores that I worked on for my PhD research, it became clear that the timing of woodland decline in Orkney differed between locations. At several sites woodland loss occurred in multiple stages, with fragments of woodland persisting into the Bronze Age in places. So it seems that woodland was present in parts of Orkney throughout the whole of the Neolithic period – but how valuable a resource would it have been to the islanders?

The tendency to dismiss prehistoric Orcadian woodland as ‘scrub’ has led to the assumption that it would not have been particularly valued as a resource by the inhabitants of the islands. Whilst it is true that the woodland was probably largely made up of species such as birch and hazel, even birch-hazel canopied woodland can be a useful and rich resource. In the North Atlantic region, environmental archaeologists have identified the management of birch woodland as one of the most pressing issues in the Norse and medieval periods. The uses of birch wood range from domestic fuel to the production of charcoal for iron smelting, and there is palynological evidence from Greenland that birch woodland was being sustainably managed, indicating the importance of the resource to the human population. In Iceland, woodland was managed by coppicing and access to woodland was controlled by the more powerful members of society. Coppice management of woodland has been practised in Europe since the Mesolithic period (c. 9000-4000 BC), with evidence provided by artefacts such as fish traps found in Ireland and Denmark. There seems to be no reason why the birch-hazel woodland of Orkney should not have been similarly valued for the range of resources that it would have provided. In fact, there may have been greater diversity in some areas, with the possibility that species such as oak and pine also grew on Orkney, and this would only have increased the range of possible uses and value of the resource. More on this in a future blog post!

 

Remains of one of the wooden structures at Braes of Ha'Breck: the large
post holes which would have held the timber uprights are clearly visible

The final question to be answered is whether the woodland of prehistoric Orkney would have been capable of providing timbers that were substantial enough for construction. Until recently, the only early Neolithic settlement known in Orkney was that at Knap of Howar on Papa Westray, which was built in stone at a time when early Neolithic houses elsewhere in Scotland were constructed from timber, thereby apparently supporting the suggestion that the predominance of stone architecture in Neolithic Orkney was a consequence of a lack of timber resources. In recent years early Neolithic buildings have been discovered at several other locations in the islands, with a wide range of architectural styles now recognised from this period. The remains of wooden structures at Wideford in west Mainland and the Braes of Ha’Breck on the island of Wyre clearly demonstrate that timber resources were exploited during the earlier part of the Orcadian Neolithic. Whilst it is probable that at least some of this timber was derived from driftwood, recent palynological evidence has shown that local woodland could have provided a more reliable resource. The archaeological evidence from Braes of Ha’Breck suggests that whilst in some cases timber buildings were directly replaced with stone structures, others may have been contemporary with them. Although stone buildings appear to have been predominant in the later phases of occupation at this site, large structural timbers continued to be used within them. A small domestic quarry on the site appears to have been exploited for its stone during the early Neolithic, when buildings were being constructed from wood, and was apparently filled in and no longer used during the later Neolithic, at a time when it has been suggested that people were turning to flagstone as a substitute for timber. This was also a period of rapid social change, and the combination of palynological and archaeological evidence suggests that the shift from timber to stone construction in the mid 4^th millennium BC in Orkney can no longer be explained simply as a consequence of a lack of timber resources. Rather than being an environmental necessity, it more likely reflects underlying social and cultural changes. 

This blog post is based on the following article, which can be accessed here:

Farrell, M., Bunting, M.J., Thomas, A. and Lee, D. (in press) Neolithic settlement at the woodland’s edge: palynological data and timber architecture in Orkney, Scotland. Journal of Archaeological Science (2012), doi:10.1016/j.jas.2012.05.042.