Methodological Approach (In Situ and Laboratory) for the Characterisation of Late Prehistoric Rock Paintings—Penedo Gordo (NW Spain)

Abstract

This paper draws on the study of the prehistoric art site of Penedo Gordo (NW Spain) resulting from a collaborative interdisciplinary research. One of its primary goals was to design and put into practice a multi-analytical protocol for characterising prehistoric rock paintings, combining in situ and laboratory analytical techniques. Thus, following the archaeological assessment of the site, the panels exhibiting red paintings were analysed by colour spectrophotometry and portable Raman spectroscopy. Analytical techniques were applied to a collection of samples exhumed from the excavation that simultaneously took place on site. These included three red accretions on different substrates (compact soil, white quartzite and grey quartzite) and stone fragments representative of the outcrop’s petrographic variability, aiming to determine their mineralogical composition, texture and study the stone-paint boundaries. Moreover, colouring materials exhumed from the excavation and collected in the immediate surroundings of the rock outcrop were analysed in order to scrutinise the provenience rock art’s raw materials. Laboratory analysis consisted of stereomicroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. One of the major outcomes was the discovery of a drop of red pigment preserved in an archaeological layer associated with Late Neolithic/Copper Age material remains.

Análisis de las metodologías para la documentación del arte rupestre. En busca de las técnicas más adecuadas

“…Para la determinación de los componentes de las pictografías, los soportes y las pátinas, así como realizar estudios sobre las alteraciones y cambios que sufren las figuras y paneles, podemos utilizar también la espectroscopia de Raman (Pozo-Antonio et al 2021). Como en los recientes proyectos de análisis de enclaves con arte rupestre en los Urales (Kiseleva et al 2023).…”

In situ characterization of prehistoric rock paintings: the Côa Valley (Portugal)

“…A combined characterisation of the chemical, mineralogical and physical properties allow us to identify deterioration forms affecting the structure of both the paintings and the backdrop, alteration agents such as water or biological colonisation, etc. [8].…”

“…As Raman and Fourier transform infrared spectroscopies have shown their portable modalities, several scientific works were found to have applied Raman spectroscopy in situ [8][9][10][11][12] to characterize prehistoric art. Moreover, colour spectrophotometry is another portable technique, which is not commonly used for the characterisation of prehistoric rock paintings, but it could be useful to perform aesthetical analyses of decorated surfaces, since colorimetric variations may indicate chemical and mineralogical alterations as was stated in [7,8].…”