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The High-Status Late Medieval Skull Shaped Relic in Turku Cathedral, Finland – a study of its origin with oxygen and strontium isotope analyses

Maria Lahtinen

Cite this as: Lahtinen, M. 2022 The High-Status Late Medieval Skull Shaped Relic in Turku Cathedral, Finland - a study of its origin with oxygen and strontium isotope analyses, Internet Archaeology 59. https://doi.org/10.11141/ia.59.8

Summary

The Turku skull relic viewed from the side showing ornate red fabric with gold thread
The Turku skull relic viewed from the side (Photo: Aki Arponen/The Turku Cathedral Relic Project, Turku University/Archaeology)

The relics and associated reliquaries of Turku Cathedral are among the most significant early Christian artefacts in Finland preserved in situ. Despite their importance, they have not been the focus of scientific enquiry for a number of decades. This study has focused on one skull shaped relic, although the origin and name of its associated saint remains unknown. The relic is the only such example with high-status decoration in the Turku Cathedral collection and is covered with a red silk decorated with yellow yarn. The bones and fabric have been dated from the beginning of the modern era to the 13th century AD, and variance among the radiocarbon (14C) dates acquired from the bones shows the remains incorporate several individuals. In this study, oxygen and strontium isotope compositions were determined from fragmented bones and textiles. The results are the first isotope analysis performed on this collection housed in Turku Cathedral. Analysis indicates an origin from outside Finland, possibly elsewhere in northern Europe or an Alpine region. This helps take us a little closer to understanding the mystery associated with this sacred artefact.

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  • Keywords: relic, medieval, Sweden, Finland, isotope analysis, strontium, oxygen
  • Accepted: 3 June 2022. Published: 21 July 2022
  • Funding: This article was published with support of Danish-Finnish Cultural Foundation and the Finnish Academy (decision number 316431).
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Corresponding author: Maria LahtinenORCID logo
maria.lahtinen@foodauthority.fi
Department of Archaeology, U. Turku
Finnish Food Authority
U. Helsinki, Finnish Museum of Natural History

Full text

Figure 1: The Turku skull relic viewed from the side (Photo: Aki Arponen/The Turku Cathedral Relic Project, Turku University/Archaeology)

Figure 2: Scatter plot of calibrated 14C probability distributions (Bronk Ramsey 2017 using calibration curve Intcal 13) of bones and fabrics (dates published in Arponen 2015 and Arponen et al. 2018b)

Figure 3: Strontium isotope compositions (see also Table 1). Fabric samples lp6A-f and lp6B-f and lp13A-f and lp13B-f are from the same textile (one is from the warp, the other from the weft). From the bone lp 8 an additional control sample was taken. Fabric samples have lower mean strontium isotope composition than the bone samples

Figure 4: Scatter plot of oxygen isotope ratios (converted using Chenery et al. 2012 and Daux et al. 2008 no. 6 formula) and strontium isotope composition of bone samples analysed in this study. Two bone samples were collected from Ip8, Ip8A and Ip8B. Oxygen isotope composition of the fabric samples has not been studied

Figure 5: Map showing the interpolation of modern mean annual precipitation δ18Owsmow (data from https://wateriso.utah.edu/waterisotopes/index.html, accessed 8.1.2018). The black shaded area indicates parts of Europe with comparable δ18Owsmow values to the range found in the study

Figure 6: Strontium isotope compositions determined from sites in Fennoscandia, Denmark and Estonia. A and B is this study; C = Denmark (Frei and Frei 2011); D = West Coast Sweden (Sjögren et al. 2009); E = Birka, Sweden (Gustin et al. 2017); F = Öland, Sweden (Fornander et al. 2014); G = Salberget, Sweden (Price et al. 2017); H & I = Iin Hamina, Finland – Salme (boat TAXIIIM), Estonia (Lahtinen et al. 2021); J = Rivers, Finland (Löfvendahl et al. 1990); K = Salme (boat TEXIC) and L = Salme (boat TAXIIIM), Estonia (Price et al. 2016); M = Estonia (Oras et al. 2016)

Table 1: Strontium isotope composition analysed in this study

Table 2: Results of the analysis of fabric pre-treatment solutions. The residue is the isotope composition of the fabric that remained after the pre-treatments.

Table 3: Oxygen and carbon isotope composition from bone carbonate. VSMOW CAC et al. has been calculated using Chenery et al. (2012) and Daux et al. (2008) conversion results using formulas 4 and 6

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