Field-Based near Infrared Spectroscopy for Analysis of Scandinavian Stone Age Rock Paintings

Abstract

During the early autumn of 2014 a field-based near infrared (NIR) spectroscopy study was carried out at Swedish and Norwegian Stone Age rock painting sites. This article presents results from one of them, namely Flatruet, Härjedalen, Sweden. Here, field-based NIR measurements were conducted using the 908-1676 nm wavelength range to gather 479 spectra: 427 of rock paintings and 52 of local lithology background. The whole dataset was analysed using principal component analysis (PCA) and four principal components were extracted explaining 98.5% (PC1), 1.4% (PC2), 0.06% (PC3) and 0.04% (PC4). The PCA results showed that there was a large spread in the spectra of both background and red paint objects, but also some evidence of clustering could be seen where background and paintings could be separated. An improvement in separation was achieved with partial least squares discriminant analysis (PLS-DA) using the background and paint as categorical variables. The most important components of the PLS-DA model showed a better separation in the score plot. A small test set of 10 paint and 10 background samples showed that one of the paint samples and two of the background samples were misclassified. One conclusion is that there is a large spread in background due to varying precipitation of secondary iron oxides. It was also decided to look deeper into local models of painted elks and their pigments alone. This was done using local PCA models and soft independent modelling of class analogies showing that some painted elks could be separated from each other while others were quite similar, which is important for answering questions about origin, age and weathering.

Environment, Archaeology and Landscape: Papers in honour of Professor Martin Bell

“…Similar combined sampling and correlated investigations had been carried out before, at the Viking Age Gokstad Ship Burial Mound near Sandefjord, Vestfold, Norway (Cannell et al 2020;. At this Sørenga D1A borehole site, standard and adapted techniques were employed, namely: soil and sediment micromorphology (Bullock et al 1985;Nicosia & Stoops 2017;Stoops 2003), magnetic susceptibility, geochemistry and micro-and macro-fossil investigations (Goldberg & Macphail 2006;Linderholm et al 2015;Viklund et al 2013). Seven borehole sediment samples were found to contain sediments disturbed during the coring process, especially Cores 2/10-2/13 and were not subsampled.…”

Near infrared and hyperspectral studies of archaeological stratigraphy and statistical considerations

“…The JDSU MicroNIR 1700 is a portable instrument to be connected to a tablet (Windows 7 based software) or laptop computer for field work. The probe is 42 mm (diam) by 42 mm (length) in size (see also Linderholm, Geladi, & Sciuto, ). It is based on an InGaAs detector and two built in quartz halogen lamps and it gives absorbances for 125 wavelengths (908–1,676 nm).…”

“…The probe is 42 mm (diam) by 42 mm (length) in size (see also Linderholm, Geladi, & Sciuto, 2015). It is based on an InGaAs detector and two built in quartz halogen lamps and it gives absorbances for 125 wavelengths (908-1,676 nm).…”

Origin and Circulation of Calcarenite Artifacts in the Area of Montescaglioso between 6th and 3rd Century BC: An Interdisciplinary Approach

“…This versatile technique is used at different scales, for reading satellite images, creating terrestrial geological maps, analyzing the lunar surface, and for mining explorations [37][38][39][40]. In archaeology, infrared spectroscopy has been widely used for surveys of aerial or satellite images [41,42] and provenance studies [24,[43][44][45][46][47][48]. All infrared spectra contain diverse information that refers to the various properties of the materials.…”