Field-based near infrared spectroscopy for analysis of Scandinavian Stone Age rock paintings
2015 (English)In: Journal of Near Infrared Spectroscopy, ISSN 0967-0335, E-ISSN 1751-6552, Vol. 23, no 4, 227-236 p.Article in journal (Refereed) Published
During the early autumn of 2014 a field-based near infrared (NIR) spectroscopy study was carried out at Swedish and Norwegian StoneAge rock painting sites. This article presents results from one of them, namely Flatruet, Härjedalen, Sweden. Here, field-based NIRmeasurements were conducted using the 908–1676 nm wavelength range to gather 479 spectra: 427 of rock paintings and 52 of locallithology background. The whole dataset was analysed using principal component analysis (PCA) and four principal components wereextracted explaining 98.5% (PC1), 1.4% (PC2), 0.06% (PC3) and 0.04% (PC4). The PCA results showed that there was a large spread inthe spectra of both background and red paint objects, but also some evidence of clustering could be seen where background and paintingscould be separated. An improvement in separation was achieved with partial least squares discriminant analysis (PLS-DA) usingthe background and paint as categorical variables. The most important components of the PLS-DA model showed a better separation inthe score plot. A small test set of 10 paint and 10 background samples showed that one of the paint samples and two of the backgroundsamples were misclassified. One conclusion is that there is a large spread in background due to varying precipitation of secondary ironoxides. It was also decided to look deeper into local models of painted elks and their pigments alone. This was done using local PCAmodels and soft independent modelling of class analogies showing that some painted elks could be separated from each other whileothers were quite similar, which is important for answering questions about origin, age and weathering.
Place, publisher, year, edition, pages
2015. Vol. 23, no 4, 227-236 p.
field-based NIR spectroscopy, rock art, chemometrics, archaeology
Research subject environmental archaeology
IdentifiersURN: urn:nbn:se:umu:diva-110315DOI: 10.1255/jnirs.1172ISI: 000368401900004OAI: oai:DiVA.org:umu-110315DiVA: diva2:862148