Getting to the bottom of Structure Five’s central hearth

By Sarah-Jane Haston

As you will be aware from my previous posts, I am looking at the carbonised plant remains from the Ness of Brodgar excavation as part of my PhD at the UHI Archaeology Institute. My research focuses on the charred remains of cereal grains, nuts, fruits and other wild plants recovered during the work in Structures Five, Eight and Ten.

The form, finds and dating of materials from Structure Five indicate that it is one of the earlier buildings within the Ness complex, dating to around 3300BC. Assessment of the plant remains from Five, and the later Structures Eight and Ten, will provide a long chronology of cultivation, gathering and wild plant use.

It was great to be part of the 2024 excavation team and particularly good to work in Structure Five, where I got a good feel for the building and the occupation deposits I will be analysing in the post-excavation phase.

There is always something special about excavating a hearth. Fire was central to people’s experience of these buildings – providing light, heat and a focus for activities in their surroundings. In excavating a hearth, you come face-to-face with the last extinguishing of that fire and can see the carbonised plant remains that fuelled it.

The types of fuel used at the Ness will be explored fully in my PhD analysis of wood charcoal and carbonised seeds from Structures Five, Eight and Ten. It is also possible to understand the intensity of the fire and possible temperatures achieved by different fuels in the colours and volumes of ash produced.

Continuous burning in the hearths the Ness would have produced large volumes of ash material, which would have been raked and spread out from the hearth setting. These deposits can be identified in the surrounding matrix and in the areas of midden material.

At the beginning of July 2024, my PhD supervisor, and fellow archaeobotanist, Dr Rosie Bishop, and I had the opportunity to continue the excavation of the hearth in Structure Five, that had been uncovered during the previous field season.

The hearth was situated along the western margin of the excavated structure and, orientated northeast-southwest, measured 1.95m in length and 0.90m in width.

The rectangular hearth was defined by six large, dressed, edge-set stones – one at either end and one long and one shorter stone making up the length of the hearth structure.

The many hearths at the Ness complex range from circular scoop hearths in the early buildings, small square hearth settings to large rectangular hearths and double hearths.

All hearth features at the Ness of Brodgar have been excavated using the single context method, where each individual context was sampled, excavated and recorded.

To obtain profiles of the stratigraphic change in the deposits, the hearth was quarter sectioned, with opposing quarters excavated. This allowed for a section drawing of the deposits on both the NE-SW and SW-NE axis. Subsequently the remaining half of each hearth was removed and sampled to allow full recovery of associated finds and environmental remains. 

Underlying the deposits, the hearth base was lined by several large, flat, flagstones. Although broken in places, these basal stones may represent one large triangular shaped stone and several smaller stones filling the interior space of the hearth.

The upper hearth deposits were composed of a bright orange-brown ashy silt, with frequent flecks and occasional fragments of charcoal and burnt bone. These deposits are likely related to material from the final phases of use within the hearth.

Similarly coloured deposits were found surrounding the hearth structure and likely relate to material raked-out of the hearth setting. A bright red ashy clay deposit, thought to represent the last use of the hearth was sampled for archaeomagnetic dating by Dr Cathy Batt from the University of Bradford.

Magnetic analysis has been integral to the research programme at the Ness complex since 2012. It uses known variations of the past magnetic field of the earth to provide a date of the last heating of the material sampled and, in the case of the hearth deposits, will usually relate to the last time that the hearth was used.

Archaeomagnetic analysis combined with the radiocarbon dating of associated material can show how the geomagnetic field changed in each fired layer. Analysis of one of the multi-layered hearths in Structure Eight showed that the hearth (hearth group 6309) may have been in use for as long as 200-300 years (Batt et al., 2020).  

Trench J supervisor Paul Durdin produced two 3d models of the excavated hearth. With these you are able to view all faces of hearth structure, getting a great idea of the size, depth and the dressing of the edge set and base stones.

The upright set-edge stones and the flat basal hearth stones were recorded by being measured, planned and photographed. The flat basal slabs were given small find numbers and will be further studied in the future.

Following recording, the basal slabs were removed to reveal a channel running in a NE-SW direction below the hearth.

The channel was lined on its upper edge by flat stones and was filled by a shallow, grey silt with occasional flecks of charcoal and fragments of burnt bone.

Once fully excavated, the hearth and underlying channel can be seen in Paul Durdin’s second 3d model of the fully excavated hearth. It appears that the channel enters Trench J on the north-eastern margin, runs east under the heath and then turns to the south-west and the primary entrance of the building.

Channels or drains like this are found on other Neolithic sites in Orkney. At the Braes of Ha’ Breck, Wyre, Orkney, Lee & Thomas (2012), in excavating the central hearth of House Five, found a stone-lined drain running downslope under the hearth’s base slab.

Drainage systems were found to be important features at a number of sites excavated around the Bay of Firth, including the Smerquoy and Stonehall (Richards and Jones, 2016).

During the Smerquoy excavations, Mainland, Gee, Richards & Robertson (2016) discovered a drainage network comprised of three different channels that were installed before the initial construction of the outer walls. They reflected that the design of the drainage network implied significant preparation of the internal space with relation to planned activities within areas of the house prior to its construction (Gee, Richards & Robertson, 2016).

Trench J Supervisor Paul Durdin details how the hearth sits on top of and truncates one of the scoop hearths associated with the earlier building, Structure Forty-One. Multiple channels were recorded running through the earlier building, one of which can be seen in the Trench J 3d model (below) running parallel to and just south-east of the channel excavated beneath the hearth.

Excavation at the Ness complex has shown that many of the buildings were built and rebuilt, constructed and amended on the base of earlier buildings. The excavation of the hearth in Structure Five and the position of the channel running downslope under the hearth base slab is an indication of the level of architectural planning involved and knowledge of local hydrology.

The technology of the hearth and channel underneath can suggest multiple uses, including to heat water and using airflow to enhance the fire, although it is more likely to relate to the bringing water in and directing water away from the building as drainage.

My post-excavation analysis of the hearth deposits will provide insight into the agricultural practices, foraging activity and fuel resources used by the Neolithic communities of the Ness of Brodgar complex. In excavating the Structure Five hearth this summer, I was able to see the value of allowing public access to witness the mechanics of the excavation and see the physical nature of the structural features as they are excavated.

Thanks to the Friends of the Ness of Brodgar for supporting my research.

References

• Batt, C., Harris, S., Outram, Z., Griffin, G. and Allington, M. 2020. Magnetic moments at the Ness of Brodgar. In Card N., Edmonds M. and Mitchell A. (Eds.) 2020. The Ness of Brodgar, As it Stands. The Orcadian, Orkney.
• Gee, C., Richards, C and Robertson, M. 2016. Local Histories of Passage Grave Building Communities: Brae of Smerquoy. In Richards, C and Jones, R (Eds). The Development of Neolithic House Societies in Orkney. Wingather Press. p64-90
• Richards, C and Jones, R. 2016. The Development of Neolithic House Societies in Orkney. Wingather Press.
• Lee, D. and Thomas, A.S., 2012. Orkney’s first farmers: early Neolithic settlement on Wyre. Current Archaeology, 268 (July 2012), pp.12-19.