STATE OF THE ART

The caves are a unique element of the underground landscape, where cultural and natural heritage come together. In Europe, some of these cavities were decorated in the Ice Age, and UNESCO ended up recognizing their heritage value, as they were the first artistic evidences of the human being. This special recognition has meant that they have been assigned special protection measures. In 1985, the Altamira cave was recognized as a “World Heritage Site”, for being an “exceptional work of human creativity” (criteria I and III). In 2008, this recognition was extended to another 17 cavities in northern Spain, including within this unique list the Biscayan cave of Santimamiñe, as well as Altxerri and Ekain (Gipuzkoa). In the French state, 25 caves in the Vézère valley, including the famous Lascaux cave, have been on the UNESCO World Heritage list since 1979. In 2014, the spectacular Chauvet cave (France) was added, and in 2016, Gorham’s cave, located on the Rock of Gibraltar (United Kingdom). The latest addition, from 2016, has included the paradigmatic German ensemble of “the art and caves of the Ice Age of the Swabian Jura”.

The Cantabrian coast is home to one of the largest concentrations of caves with Paleolithic art in the world. According to our latest list, to date 158 sites are known to be safely decorated in the Paleolithic (to which up to 18 more doubtful assemblages would be added), from the Nalón river basin (in the west), to the Urdazuri river in the east , welcoming the autonomous communities of Asturias, Cantabria, Euskadi and Nafarroa. Even so, until 2001, the situation was very different in Euskadi and Nafarroa, since only seven decorated caves were known (Venta la Perra, Arenaza, Santimamiñe, Goikolau, Ekain, Altxerri and Alkerdi). In the first decade of this new 21st century, occasional random finds were made within the framework of archaeological interventions carried out in some Basque cavities (Antoliña, El Rincón, Praileaitz and Astigarraga). However, since the discovery of Askondo in 2011, the research team led by Diego Garate, in the company of speleology groups (ADES, Felix Ugarte Elkartea, Satorrak) and archeology (Antxieta Jakintza Taldea), have radically revolutionized the panorama of rock art in Euskal Herria. In total, the list of known decorated caves has been quadrupled, and in addition to some modest sets, due to their reduced number of figures or precarious state of conservation (such as Morgota, Ondaro or Agarre), it has also been possible to discover spectacular pictorial sets, in an exceptional state of conservation (Atxurra and Armintxe in Bizkaia, and Aitzbitarte IV in Gipuzkoa). Furthermore, this research team has managed to develop a GIS system to facilitate and optimize these prospecting tasks.

In terms of the protection of the cave, in recent decades some of the caves in the Basque Country -Arenaza, Santimamiñe, Armintxe, Altxerri and Ekain- have been monitored (humidity, temperature, radon, CO2, atmospheric pressure, etc.). Apart from this, occasional measurements and monitoring have been carried out in other caves -Atxurra, Venta la Perra, El Rincón, El Polvorín, Aitzbitarte III, IV, V and IX-. Following this line, in 2021, the “Kobabes” project studied three caves (Santimamiñe, Lumentxa and Altxerri), analyzing their past and present dynamics, and building protection maps “macro” (whole cave) and “micro” (panel). specific) level.

However, like all cultural heritage, the number of representations of cave art is limited and tends to be places of high fragility (Figure 2). This fragility will depend on the relationship between the material representing the cliff art and the environmental conditions. With this in mind, when materials are painted, they can be iron oxide (red), coal (black), and manganese oxide (black) pigments (Chalmin et al., 2003). When they are engraved, the characteristics of the material belong to the same rock as the representation. In terms of environmental conditions, cave art is mainly found in caves, which are areas where there is 100% humidity, relatively stable temperatures, where CO2 is more abundant than in the atmosphere, and so on. In general, these conditions are quite extreme conditions, and it is accepted that a machine made during the Paleolithic period has disappeared to the cliffs because they have not survived in these conditions.

Some of these environmental conditions are unlikely to change over time (for example, humidity will usually always be 100% in caves in the Basque Country), while other conditions will respond to the environmental conditions outside the cave and the geological dynamics of the cave. Given the dependence of cave art protection on environmental conditions, many studies have been conducted in caves containing this cultural asset, always focusing on environmental condition monitoring (e.g. Dragovich, 1981; Brunet, Vouvé, 1996; Hoyos et al., 1998; Coye , 2011; Sánchez-Moral et al., 2014; Leplat et al., 2020).

Some of these studies have established the limits on the number of visitors to the cave and the cave art it preserves in order to provide sustainable visits. The fact is that with these types of research, the current state of cave art is mainly defined, but not so much the evolution of environmental conditions in the short-medium term. In other words, they are effective in dealing with a momentary situation at the moment, but not so much in anticipating situations that will arise in the future.

JUSTIFICATION AND GOALS

The general objective of this project is to carry out a study aimed at protecting the rock art of the decorated caves of the Basque Autonomous Community, through in-depth graphic documentation of some parietal images. To do this, we have designed a useful methodology to understand the evolution of rock art in caves throughout an annual cycle through the use of cutting-edge technologies. We anticipate the use of innovative technologies in digital photography in particular, updating and improving the current digital archive, which will be useful for conservation, research and public dissemination. To do this, we propose to analyze some cave figures from the Santimamiñe (Kortezubi, Bizkaia), Lumentxa (Ispaster-Lekeitio, Bizkaia) and Altxerri (Aia, Gipuzkoa) caves, studied in the previous “Kobabes” study, by applying an innovative methodology. Once the results of the two projects have been combined, this methodology could be extended to the rest of the decorated caves in the Basque Country, ensuring effective monitoring for their protection.

Taking into account the above, to fulfill the general objective and the work to be carried out, a series of specific objectives (SO) have been set, always adapted to the duration of the project:

SO1- Photogrammetrically document some panels studied in the previous year (to prepare cartography for their protection) in two of the three selected caves (Lumentxa and Santimamiñe) in different seasons of the annual cycle (hot and cold phases, wet and dry phase, etc. .).

SO2- In the laboratory, process the documentation obtained in the cave, obtaining colorimetrically and geometrically correct color replicas. This would provide a realistic replica of the panel at each specific time of year, which could be useful for both research and public outreach.

SO3- Compare the replicas obtained by analyzing the cyclical evolution of cave paintings (measuring colorimetry) and the evolution of the wall (condensations, reproduction of fungi or bacteria, micro-destruction, etc.). Compare the results observed with those obtained in the “Kobabes” project, designing a protection protocol that will be applicable to the rest of the caves in the Basque Country.