Earth Sciences for Cultural Heritage

Characterizing fossils and quantifying paleoenvironmental proxies at a detailed scale is a significant challenge. Three-dimensional tomographic reconstructions are becoming increasingly common, and new imaging approaches, such as synchrotron-based fast X-ray scanning and full-field multispectral imaging, now provide the means to (1) describe fossil morphology at a very fine scale, (2) decipher long-term alteration processes, and (3) better identify conservation requirements.

Understanding how painted works of art were constructed, layer-by-layer, requires a range of macroscopic and microscopic X-ray and infrared-based analytical methods. Deconstructing complex assemblies of paints horizontally across a picture and vertically through it provides insight into the detailed production process of the art work and on the painting techniques and styles of its maker. The unwanted chemical transformations that some paint pigments undergo are also detectable; these changes can alter the paint’s optical properties. Understanding the chemistry behind such paint degradation gives conservators vital clues to counter these effects and is an invaluable asset in protecting these cultural artifacts for future generations.

The scientific investigation of works of art has an essential role in understanding museum collections and is fundamental in establishing successful conservation and restoration strategies. In the multidisciplinary environment of museums, scientists work with conservators and curators not only to more profoundly understand works of art but to better preserve them, and this often involves using analytical techniques borrowed from different disciplines of Earth sciences (e.g. mineralogy, geochemistry, and petrology). Two case studies – the stones of Angkor (Cambodia) and a blue paint mineral pigment – demonstrate how the Earth sciences are helping to identify, determine provenance, and conserve a broad spectrum of works of art. The impact on archaeological and art historical scholarship is substantial.

This article reviews optically stimulated luminescence (OSL) dating as used on Quaternary sediments and for archaeological dating. The underlying physics is summarized and the laboratory method itself is described. Examples of OSL dating illustrate its use in palaeoenvironmental and archaeological contexts, although problems associated with the technique are also addressed. Finally, we discuss long-range variants of OSL that may help date deposits currently considered too old for OSL to be applied.

Archaeological geophysics is a vital part of exploring and documenting cultural heritage. Three of the most commonly used techniques are magnetometry, resistivity, and ground penetrating radar. These methods help archaeological geophysicists to unravel the complexity of many archaeological sites, including urban ones, old buildings, and built structures of cultural importance. However, local factors, such as constraints on time, local environment, pre-existing available information, and budgets, all contribute to a given site requiring unique geophysical surveying strategies. Four Spanish-based, but generally applicable, case studies will illustrate key geophysical strategy types for particular local archaeological conditions.

This issue of Elements celebrates the diverse contributions that the Earth sciences have made to characterizing, interpreting, conserving, and valorizing cultural heritage. Archaeometry and conservation science are connected to the geosciences at different levels. Earth scientists possess a profound perception of the complexity of natural materials, they have the necessary knowledge of the ancient and recent geological and physico-chemical processes acting on natural materials and on the artifacts produced by human activities, and they master most of the techniques useful to investigate our common heritage. Therefore, Earth scientists can greatly contribute towards a better understanding and preservation of our past.