HEAD HUNTING IN THE HIGHLANDS – Using archaeological science to understand extraordinary medieval burials from St Colman’s Church, Portmahomack, Tarbatness, Highlands

The next post in our British Science Week 2020 series is about a project supported by funding from Historic Environment Scotland, a NHSF member. 

Written by Cecily Spall, FAS Heritage

Image 1 - 3-D scans - credit Visualising Heritage, UoB
Image 1: 3-D colours scans of the skull of Chieftain A (right) showing blade cut and Chieftain B (Credit: Visualising Heritage, University of Bradford)
Image 2 - Chieftain A and skulls - credit FAS Heritage
Image 2: Chieftain A with the four extra skulls set at his head (Credit: FAS Heritage)
Image 3 - Chieftain B reconstruction - credit FaceLab LJMU
Image 3: 2-D computer-based facial reconstruction of Chieftain B (Credit: FaceLab, Liverpool John Moores University)

The Tarbat Discovery Centre, Portmahomack, opened in 1999 in the former medieval church of St Colman.  It displays the results of 20 years of archaeological research excavation focussed around this important church.  Along with National Museums Scotland, the Centre cares for the collection of burials, dating from the 7th to the 16th century, excavated from in and around the church building.

St Colman’s Church was built in the 12th century in the abandoned burial ground of an 8th-century Pictish monastery. Burials continued from the 13th to the 16th century. Over 80 medieval burials were excavated and include a small group of burials which were highly unusual, displaying burial rites never before seen.  The central burial was that of an older man – ‘Chieftain A’ – who had died aged 46 to 59 years from a horrendous facial injury caused by a blade (Image 1). On his death he was interred in a large coffin which included four extra skulls set at his head (Image 2). About a generation later his grave was reopened and the body of a second man – ‘Chieftain B’ – was laid on top with the skulls now set around his head.

A Historic Environment Scotland funded programme of archaeological scientific analysis is now underway, designed to better understand these extraordinary burials. This includes radiocarbon dating and ‘Bayesian’ (statistical) modelling of the dating brackets to refine them. The results suggest that Chieftain A died between AD1290 and 1410 and Chieftain B between AD 1380 and 1450; three of the skulls buried with them died between AD1250 and 1400 and the fourth belonged to a Pictish monk who died between AD770 and 900. These extraordinary burials belong to the period when the clan system was becoming established and so represents an important part of understanding Highland heritage and the history of the community of Portmahomack.

Multi-isotope analysis measuring strontium and oxygen preserved in tooth enamel has also provided information on region of birth with Chieftain A having grown up on or around the Tarbatness peninsula, and Chieftain B growing up elsewhere, perhaps in the Western or Northern Isles, moving to Portmahomack later in life.

Computer-based reconstruction of the face of Chieftain B has been undertaken using European datasets to model his likely appearance (Image 3), work which was generously funded by the Society of Antiquaries of Scotland. Ancient DNA analysis is also underway at Harvard University and it is hoped that it will provide information on possible family connections between the burials, as well as likely skin tone, and eye and hair colour, and perhaps even his deeper shared ancestry.

The Tarbat Discovery Centre is currently hosting a temporary exhibition on the burials project. For more information visit: http://www.tarbat-discovery.co.uk.

Traineeship in Heritage Science at Historic Environment Scotland

The latest blog in our British Science Week 2020 is written by Meghan Godley.

This is the first in a series of blogs which we will post over the next few days from Historic Environment Scotland, each of which will showcase the work of a different department. 

My background is in geology having just graduated from my master’s geoscience degree. My research looked at the geochemistry and petrology of the Ross of Mull granites, which is one area of geology that I have a very strong inclining towards. On completion of my degree I was interested in expanding my laboratory skills in a whole new sector. I always had a passion with history and heritage, so this was the perfect mix while I can still progress my learning.

The conservation science traineeship provides an excellent opportunity of experience and training in a range of materials testing and different analytical techniques, targeted towards understanding the behaviour of building materials regarding future conservation challenges, including the threats of climate change. One issue that we face when conserving our traditional buildings concerns the sourcing and replacement of historic roofing slate.

By using a piece of equipment known as a chromameter we were able to quantify the colour of different historic slates and use this information to help identify the original source region of the slates and the most appropriate replacement slates to be used.

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Image 1. Left; Chromameter analysis on a slate in the laboratory. Top Left; roofing slate from Stirling Castle Top Right, slate from Aberfoyle quarry Bottom right; Graph showing the results of analysis, highlighting the diversity of their colour in Scotland. Images © Historic Environment Scotland. 

By undertaking scientific analysis of traditional building materials and conducting on-site condition monitoring, the conservation science team supports the making of informed conservation decisions in order to protect HES’s properties in care.

One technique we use is X-ray Diffraction (XRD) analysis, which uses X-rays to determine the minerals present in a material. This technique was used to understand the composition of repair material to a window in the King’s Old Building’s at Stirling Castle. We identified that the material was made from a lime putty and contained several layers of paint, which contained white lead. Health and safety precautions were then put in place to ensure the safe removal of the material.

Having studied geology at university, I never thought that I’d ever be analysing the composition of glass! Recently Dr Maureen Young and I were asked to analyse some glass window panes from Edinburgh Castle to help determine their age. By using a technique called X-ray Florescence (XRF) we can measure the chemical composition of the glass. By identifying specific elements within the material, we can help date the glass, according to the changing manufacturing processes used in Scotland. The panes dated to post 1930’s, indicating the glass had been replaced during repairs to the windows recorded at this time.

HES Blog 1 Image 2
Image 2. Dr Maureen Young using portable XRF on the glass at Edinburgh Castle. Image © Historic Environment Scotland. 

By utilising these newly learnt skills, I’m now conducting my own research project concerning the characterisation and potential climate-change impacts on the Achnabreck rock carvings in Argyll. This site provides some of the best examples of prehistoric rock art in Scotland. By better understanding the composition of the geology at these sites, we can help mitigate the risk to the threats of climate change and help preserve their conditions for future generations.

HES Blog 1 Image 3
Image 3. Image of Achnabreck rock carvings site that is to be analysed. Image © Historic Environment Scotland. 

 

British Science Week 2020: Heritage Science Events

In our second blog post for British Science Week 2020, find out about some of the very exciting heritage science events that are taking place over the next week…

Zoom-In: a closer look at science, British Museum, London

The British museum are offering you the chance to discover how their scientists and conservators unlock the secrets behind the Museum’s collections. The event will mark the 100th anniversary of the opening of a research laboratory at the Museum. As part of celebrations, you will learn about the different techniques that are currently used to monitor and preserve collections and observe the latest technology.  You will also have the opportunity to handle different kinds of raw materials.

Events will be taking place in the Museum’s Great Court all day on Saturday 14th March. Just drop by; there is no need to book beforehand. More details can be found here.

Taking place Thursday 12 March, 9 am- 5 pm. You can book your ticket here.

British Science Week at the Mary Rose, Portsmouth

The Mary Rose Trust has partnered with Zeiss Microscopy to offer visitors an insight into the science used to preserve its collection. You will have the opportunity to see the objects in more detail than ever before and to hear from experts.

Taking place Friday 13- Sunday 15 March. More information available here.

Attend a talk on Bristol’s link with the history of photography and take part in a selection of light and time based experiments, including seeing how the world would appear without a brain. There will also be the opportunity to watch sensitive silver salts become black and white images in a photographic Darkroom.

Events taking place on Saturday 14 March, 1-4 pm. More information here.

The pannotype mystery: using science to research early photographic processes

This year we are again using the wonderful opportunity of British Science Week (6th – 15th March) to showcase brilliant examples of heritage science work being undertaken by NHSF members and across the sector more generally.  We will post new blogs throughout the coming week. 

To launch the series, we have a post written by Ioannis Vasallos, Conservator of photographs and paper at The National Archives, all about the analysis and conservation of rare photographic processes.

The National Archives has an estimate of eight million photographs in its collection. Some of the very early ones can be found on the Design Registers, which contain almost three million British patterns, products’ designs and trademarks from 1839 to 1990s (figure 1). As part of a larger project to understand, conserve and improve access to the Design Registers, Collection Care has been doing research and analysing some rare examples of early photographic processes found amongst them.

Pannotype is an early photographic process invented in 1850s, and used only for a short period of time till the 1880s. Photographs made with this process are rare in collections, and it is therefore exciting to have found 15 pannotypes in a bound volume of the Design Registers (figure 2). These photographs depict designs of ceramic houseware but many of them cannot be accessed due to their deteriorated image layer which has become tacky, and caused other designs to stick on them (figure 3).

A series of analytical techniques were performed in order to understand the composition of the image layer, as well as the rest of the materials that the photographs are made of. Elemental analysis was done with X-Ray Fluorescence spectroscopy (XRF) and showed us the presence of silver particles (figure 4), which confirms the photographic nature of the image. Lead was also detected and seems related to the manufacturing of the cloth support that the pannotypes were placed on. Fourier Transform Infra-Red spectroscopy FTIR analysis identified a natural resin on the photographs whose image layer is degraded, and collodion on others whose image is not affected (figure 5). The analysis helped to combine literature review of historic photographic journals and photographic recipes in order to cross reference the materials that were identified. Finally, the newly acquired Multispectral Imaging system (MSI) was also used to enhance the visibility of the images on the pannotypes whose surface is covered by stuck pieces of paper (figure 6 & 7).

This will now inform the decision making for the conservation of the photographs whose image is degraded and have paper stuck on their surface. The information gained will also enhance the understanding of historic photographic practices helping to preserve similar photographs in other archives and collections.

To find out more about the work of Collection Care you can check the blog of The National Archives at https://blog.nationalarchives.gov.uk/, or you can contact Ioannis Vasallos, Conservator of photographs and paper Ioannis.Vasallos@nationalarchives.gov.uk

NA figure 1
Figure 1: BT 43/67, an open page in a volume from the Design Registers. © The National Archives.
NA Figure 2
Figure 2: BT 43/67, pannotype depicting pottery. © The National Archives.
NA Figure 3
Figure 3: BT 43/67, Group of pannotypes with paper stuck on their surface. © The National Archives.
NA Figure 4
Figure 4: XRF analysis on a pannotype photograph. © The National Archives.
NA Figure 5
Figure 5: Conservation scientist, Lucia Pardo Pereira perform FTIR analysis on a pannotype photograph. © The National Archives.
NA Figure 6
Figure 6: BT 43/67/130678, true colour image captured with MSI. © The National Archives.
NA Figure 7
Figure 7: BT 43/67/130678, infrared reflected (IRR) image captured with MSI. © The National Archives.

Upon Closer Inspection…

Author: Joshua Bobbett, National Trust

Looking at analytical techniques and equipment during NHSF and UCM’s workshop ‘What can heritage science do for you?’

I attended the workshop entitled ‘What can heritage science do for you?’ on the 12th March 2019 at the British Library, held as part of British Science Week. Dr. Paola Ricciardi and Dr. Lora Angelova supported by the excellent staff at the British Library’s conservation department were able to provide a whistle-stop tour through the use and benefits of:

  • FTIR
  • Portable XRF
  • IR Imaging
  • Raman Spectroscopy
  • FORS
Joshua blog 1
Practical applications of analysis equipment along with the pros and cons of certain equipment were explored.

Exciting case studies of current analytical work were presented and used to colour the reasons of how heritage science can complement the usual glamour of engagement at our museum and gallery exhibitions. A personal highlight was discussion on the recent analysis of Isaac Oliver’s cabinet miniature of Lord Herbert of Cherbury (on display at Powis Castle in Mid Wales). Using the equipment listed above, Dr. Ricciardi’s explanation of how analysis brought forward the mystery of how Oliver may have learnt the art of cabinet miniatures in Flanders and not Britain as previously thought, based upon the analysis of green copper sulphate pigments displayed how these machines can offer so much more than just identification and data.

Joshua blog 2
Interpretations of spectra were shown to give ideas on further application of the equipment for our own collections.

The practical session during the afternoon gave the chance to get hands on with the equipment and get a good idea of the intended use, reliability and cost of each machine. The range of equipment and knowledge available during the day was able to complement all levels of experience, yet highly recommended for those employed in the heritage sector that are curious about covering another aspect of collections care which can often take place under the radar.

It is well worth keeping an eye out for more training and workshops from the NHSF on ICON’s website and if you’re employed in the heritage sector, checking if your own organisation is a member too!

What can Heritage Science do for you? ‘Framing research questions and developing research projects’

Author: Veronica Ford

In this opening section of the workshop Lora and Paola focused on how to clearly and carefully frame research questions and how museum professionals can establish a constructive dialogue with the heritage scientist carrying out the research. The need to set realistic, manageable, and targeted research goals was rightly emphasised, with the course leaders suggesting a frequent pitfall was for researchers to be too ambitious with their aims – for instance requesting all pigments on a painting are analysed as opposed to just one or a select few.

It was shown that it is fundamental that the correct data is gathered in the correct way for a research project to be successful. To determine this it is important to be clear what analysis is being used to inform. The course leaders divided research projects into two principle types: practice based and practice led. Many curatorial questions about an individual object fall under the category of practice based research, such as determining the authorship, provenance, and composition of an object. Practice led research, in this context, can often involve determining the correct conservation technique for a particular object or group of objects.

One of the major strengths of the workshop, and this section in particular, was how the course leaders liberally used case studies to elucidate and contextualise their examples of research questions. This helped to show the potential scope of research projects. For instance, visible light induced luminescence was used to help determine the provenance of a manuscript from Cambridge University which had both Frankish and English elements. Analysis indicated that the blue pigment of the manuscript contained Egyptian blue, a pigment which is found more regularly in English not Frankish manuscripts of this era, thus indicating that the manuscript was likely of English manufacture. This example showed how important research questions can be answered through the careful selection of specific analytical techniques to analyse specific datasets.

Particularly beneficial was how the course leaders, as heritage scientists themselves, acknowledged the unique problems and limitations of working within the heritage sector, such as the need to create representative aged samples to carry out testing. At the root of the course was an awareness that conservators often tread the fine line between the objective and the subjective when making conservation decisions, as well as what this means when interacting with scientists – particularly those that are not heritage scientist specialists – who tend to work well within the realm of the objective.

Veronica Ford (veronica.ford@bodleian.ox.ac.uk) is an Assistant Preventive Conservator at Bodleian Libraries (@BodCons ). 

 

Reflections on our ‘What can heritage science do for you?’ workshop

Over the next week, we will be publishing reflections from attendees of our ‘What can heritage science do for you?’ workshop that we held in partnership with the University of Cambridge Museums (UCM) back in March.

The one-day workshop took place at the British Library to explore the benefits of heritage science research in the context of collections-based research and outreach activities.

Participants learnt about a range of analytical methods, which methods can be used to learn more about the materials composition, history, original context and current conservation and storage needs of archaeological, archival and museum objects.

During the workshop, real case studies of heritage science research applied to a range of objects were presented and discussed.

Participants were asked to contribute their experience of, or aspirations for, collaboration with heritage science researchers. The workshop was targeted at conservators, curators, early career scientists, collections managers, archivists and librarians working in museums, archives, libraries and historic houses.

A limited number of free places were available to employees or members of NHSF member organisations.

Keep an eye out for out upcoming posts!