Wednesday, 13 November 2013

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 4th 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.


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