Orkney’s bogs hold the key to the islands’ prehistoric past

Coring at Blows Moss, South Ronaldsay, from which they retrieved 7m of peat. Michelle Farrell being assisted by Dr Barbara Rumsby and Sandra Pratt.

After three weeks wading through some of Orkney’s dankest bogs, a Hull university student hopes her investigation will answer some questions about the islands’ prehistoric past.

Michelle Farrell and Dr Jane Bunting, from the University of Hull, have been in Orkney to collect marshland samples in the hope that their study will answer, once and for all, what happened to Orkney’s population from the Bronze Age onwards.

There has been a long-held assumption that the population of Orkney declined through the Bronze Age, as the climate deteriorated. Increased rainfall and falling temperatures meant, it has been suggested, life became harder and resulted in an exodus from Orkney.

A population decrease has long been cited as the reason for the apparent lack of Bronze Age remains in Orkney – at least in comparison to those from the Neolithic.

But did this exodus actually take place? Or was there simply a change in lifestyle that saw people moving around to make the most of the remaining fertile soils? Did the agricultural emphasis switch from cultivation to animal husbandry?

Michelle’s research is part of her work for a PhD on the Palaeoecology of Orkney and past human occupations, and hopes to provide some answers.

She explained: “Although much is known about the archaeology of Orkney, very few studies have attempted to reconstruct the environment of the islands during the Holocene.

Picture: Jane Bunting

Michelle Farrell and Lynda Yorke coring near the Dyke of Sean, Ness of Brodgar.

“Of the palaeoecological studies that have been carried out in Orkney, the majority concentrate on the West Mainland. Currently there are records from only three areas (the West Mainland, Rousay and southern Hoy), although potentially suitable coring sites have been identified on Westray, South Ronaldsay and Eday.

“There are also large areas of northern Hoy and eastern Mainland that had never been palaeoecologically investigated. Another feature of previous palaeoecological studies in Orkney is that they have tended to focus on the Neolithic period and the pre-Neolithic landscape, and the Bronze Age environment has never been properly explored.”

Picture: Jane Bunting

Michelle Farrell and Dr Barbara Rumsby coring at Whaness Burn, between the Dwarfie Stane and Bronze Age settlement, Hoy.

But now, cores have been taken from peaty sites in the West Mainland, Hoy, Westray, Minehowe in Tankerness and South Ronaldsay. Analysis of pollen grains found in these “environmental archives” will document how the vegetation changed over time, which allows an interpretation of how the land was used.

Every time a plant produces pollen, most of it will eventually end up on the ground. In most environments, these pollens decay but in peat bogs and lochs, the grains are preserved in the acidic or waterlogged conditions.

In stable bogs and lochs, peaty sediments containing pollen and the dead remains of plants and microscopic animals accumulate in chronological order, and can be preserved for thousands of years.  Any hay fever sufferer knows that pollen grains are abundant and widely distributed!  .

Michelle hopes her Orkney pollen samples will allow her to build up a picture of land use around the sample sites through the millennia – land use that would alter were there any dramatic change in Orkney’s population.

A drop in cereal cultivation, for example, would be represented by a decline in cereal pollen along with an increase in pollen from weeds and grasses that would grow in the former cereal fields.

Even at this early stage of the project, the coring process itself has provided an intriguing glimpse as to how Orkney’s landscape has changed since prehistory.

Samples taken at Blows Moss, in South Ronaldsay, revealed peat deposits over seven metres deep. The sheer depth, together with deposits of wood buried deep in the marsh, hints the area was once loch, perhaps surrounded by woodland.

Sprettameedo, in Kirbister, Stromness, is another example.  Still very wet and boggy today, the site contains over 3.5m of sediment. Sediment from the bottom of the basin is not peat, but lake sediment, suggesting that it too was once a loch.

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