Palaeoecological investigation of Brodgar’s past landscapes

Friday, April 7, 2023

Sue Dyke alongside sections of the full length of a pollen core taken from an Orkney loch, ready for freezer storage. (Sara Marinoni) — Sue Dyke alongside sections of the full length of a pollen core taken from an Orkney loch, ready for freezer storage. (📷 Sara Marinoni)

Sue Dyke, a UHI Archaeology Institute Masters by Research (MRes) student, started palaeoecological investigations around the Ness in February.

Her goal is to reconstruct the prehistoric vegetation around the Ness of Brodgar peninsula, across a period (c. 43000 cal BC to 2000 cal BC) that includes times of active usage of the Ness complex.

The focus of the research will be upon two important transition periods, the Late Mesolithic to Early Neolithic (c. 4300 to 3300 cal BC) – the time when the Ness complex was becoming established – and Late Neolithic to Early Bronze Age (2600 to 2000 cal BC), the time following the decline and disuse of the prehistoric site.

Sue will be analysing pollen, non-pollen palynomorphs (NPPs) and microscopic charcoal in sediment cores, taken from the Loch of Stenness by the Rising Tides project in 2014 (Bates et al. 2012, 2016, Bunting et al. 2022).

What is pollen analysis?

Figure 2 - Microscopic views from a pollen analysis showing non-pollen palynomorph (NPP) environmental indicators, microscopic charcoal revealing fires in the landscape and pollen grains showing prehistoric plant communities that grew in the landscape. — Figure 2 – Microscopic views from a pollen analysis showing non-pollen palynomorph (NPP) environmental indicators, microscopic charcoal revealing fires in the landscape and pollen grains showing prehistoric plant communities that grew in the landscape.

Pollen analysis is a technique for reconstructing former vegetation by means of the pollen grains it produced (Moore Webb and Collinson 1991).

Analysis also includes recording of aquatic taxa, fern and moss spores, non-pollen palynomorphs (NPPs – fungal spores, algae and microzoological remains) and microscopic charcoal deposited (Fig 2).

Pollen grains are often preserved in waterlogged conditions in wetland environments including lake sediments, sometimes for tens of thousands of years.

The different shapes and surface patterning of pollen grains allow identification to family and genus level of past plant communities.

Pollen can be dispersed by wind, water, or insects, but most fossil pollen is windborne, this pollen “rain” gets laid down in sediment layers forming stratified sequences over time.

Taking a vertical core sample through sediments allows past plant communities, and their environments, to be studied and can also reveal human activity in, and interaction with, the surrounding landscape.

The sections of pollen core (Fig 2) are sub-sampled for pollen (Fig 3), radiocarbon dated to accurately age the different layers and then microscopic analysis can take place.

Figure 5: Sub-sampled pollen core. (Sue Dyke) — Fig 3: Sub-sampled pollen core. (📷 Sue Dyke)

What can palaeoenvironmental analysis tell us about prehistoric landscapes and the people dwelling there?

Figure 3 - Layers of loch sediment in a pollen core within a closed chamber auger. (Sue Dyke) — Figure 3 – Layers of loch sediment in a pollen core within a closed chamber auger. (📷 Sue Dyke)

Pollen analysis can reveal how prehistoric people used and interacted with past landscapes, for example, first settlers creating woodland clearances through burning can result in decreased tree pollen and associated microscopic charcoal “spikes” in the pollen record.

Agricultural practices can be elucidated through identification of cereal and associated arable weed pollen demonstrating arable cultivation, whereas increased levels of grass pollen and dung fungal spores signal grazing animals in pastureland (Figs 4 and 5).

Sue’s MRes results will provide a window onto the prehistoric landscapes that surrounded the Ness of Brodgar, reflecting the presence and activities of the people living and working the land there and give insight into how past environments influenced and were affected by the local population.

Data produced will also be used to enhance existing “vegetative modelling” of Orkney’s West Mainland during the Neolithic.

Sue is currently based at UHI’s Orkney College campus, where she graduated in September 2022 as part of the first UHI Archaeological Science BSc Hons cohort.

Figure 6 - Some pollen associated with agricultural activity — Fig 4: Some pollen associated with agricultural activity.

Figure 7 - Dung fungus and Ribwort Plantain pollen (a pollen indicator of disturbed ground) — Fig 5: Dung fungus and Ribwort Plantain pollen (a pollen indicator of disturbed ground).

During her undergraduate studies she received sponsorship for pollen analysis from the Association for Environmental Archaeology, Orkney Archaeology Scociety (OAS) and the UHI Student Scholarship Fund to investigate Orkney’s First Settler landscapes in South Ronaldsay.

A subsequent pollen analysis for community archaeology project Tarradale Through Time (Muir of Ord) was associated with an Iron Age Marsh Fort, and sponsored by a Society of Antiquaries of Scotland Student Fellow Grant, UHI Student Development Fund and OAS.

Sue’s undergraduate final dissertation used fine-resolution pollen analysis, supported by archaeological survey and historical documentary evidence to investigate the land-use, economy, and environmental impact of postmedieval shielings at Braehour.

Her dissertation was awarded the UHI’s Best Undergraduate Archaeology Dissertation Prize, and also won the 2022 John Evans Masters Dissertation Prize. She presented her research at the 2021 Highland Archaeology Festival, and as an Instagram poster at the Post-Medieval Archaeology Congress 2022.

Sue’s MRes is supervised by Associate Professor Scott Timpany (UHI Archaeology Institute), Professor Jane Bunting (Hull University) and Assistant Professor Michelle Farrell (Coventry University).

References

Bates, R., Bates, M., Dawson, S., & Wickham-Jones, C. (2012). Geophysical Survey of the Loch of Stenness, Orkney. Aberdeen: Aberdeen University
Bates, C. R., Bates, M. R., Dawson, S., Huws, D., Whittaker, J. E., & Wickham-Jones, C. R. (2016). The environmental context of the Neolithic monuments on the Brodgar Isthmus, Mainland, Orkney. Journal of Archaeological Science: Reports, 7, 394-407.
Bates, M. (2022) Rising Tides – Caroline Wickham-Jones Memorial Lecture, Orkney International Science Festival 2022. Accessed online [ https://oisf.org/fest-event/rising-tides/ ] 13th March 2023
Bunting, M. J., Farrell, M., Dunbar, E., Reimer, P., Bayliss, A., Marshall, P., & Whittle, A. (2022). Landscapes for Neolithic People in Mainland, Orkney. Journal of World Prehistory, 35(1), 87-107.
Moore, P. D., Webb, J. A., & Collinson, M. E. (1991) Pollen analysis. Oxford: Blackwell Scientific Publications.
Wickham-Jones, C. (undated) The Rising Tide: Investigations into the Submerged Archaeology of Orkney https://www.abdn.ac.uk/geosciences/departments/archaeology/the-rising-tide-investigations-into-the-submerged-archaeology-of-orkney-261.php Accessed online [07/03/2023]