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.

Even so, and as with other cultural heritages, the number of representations of Basque rock art is limited, and they are sets of enormous fragility. This extreme fragility will be largely conditioned by the balance produced between the characteristics of the material that supports the representations and the different environmental parameters of the caves. The rock art of the Autonomous Community of Euskadi is located exclusively in endokarst cavities, that is, in places with a humidity close to 100%, a relatively constant temperature (except in those cases in which the letters are located in external areas, such as this would be the case of Venta la Perra or Askondo, for example), and an amount of CO2 that is higher than that accumulated in the open air. In general, these are relatively extreme environmental conditions, and it is estimated that an unknown number of Palaeolithic representations have not survived to this day for these conservation reasons.

Despite the fact that some of these environmental parameters will hardly undergo modifications (for example, it is estimated that humidity will always remain close to the saturation level inside the cavities of the Autonomous Community of the Basque Country), it is possible that certain conditions experience adaptations to external environmental conditions, as well as to the geological dynamics of the caves. Taking into account that the protection of the rock art in these caves is closely linked to these environmental parameters, there have been numerous projects to study these conditions in those cavities that contain this cultural heritage (including some in the Basque Country). These studies have been limited almost exclusively to a general monitoring of these environmental conditions, as well as to other types of monitoring linked to conservation (e.g. presence of fungi, cleaning of residues, etc.)

Taking into account the current context of global climate change, we consider priority those measures that are undertaken to solve the conservation problems that concern these special contexts (decorated caves), especially to prevent situations that have no turning back. The absence of a common legal framework, and the incompatibility between some protection regulations, produces situations of risk and lack of protection, which end up directly affecting the conservation of these cultural heritages.

In this sense, our project is a novelty that can be of great help to achieve effective protection for this first-rate cultural heritage that is cave art. From the joint study of two different elements of the endokarst (the geological dynamics of the caves and the environmental parameters), and through collaboration between different disciplines (archeology and geology), we will try to enable an improved management for the protection of these unique monuments, proposing a regulation consistent with each case.

JUSTIFICATION AND GOALS

In order to achieve measures that guarantee the effective protection of the Paleolithic rock art in the Basque Country, it is necessary to know the current and past dynamics of its natural containers -the caves- (know the genesis of the cavity, identify and chronologically characterize the processes that have given rise to shape the current state of the underground landscape, identify the most sensitive areas of the caves, etc.). However, it is not an easy task, since each cave is conditioned by its own parameters that affect it in a unique way, despite the fact that other conditions are generalized and common to all (for example, relative humidity rates)

Through the KOBABES project, we have chosen a series of cavities, to monitor their environmental parameters (humidity, CO2, temperature, etc.) and to know and identify the processes that have taken part in their genesis (allostratigraphic units, speleothem study , U / Th dating of the sedimentation processes, etc.). All this will be achievable thanks to the documentation available from the public administrations in charge of its protection -the cultural heritage services of the Provincial Councils of Bizkaia and Gipuzkoa- (3D models, periodic monitoring carried out in previous annuities, etc.), that will allow us to design protection protocols applicable to other caves, and to design planimetries and risk models using geographic information systems (GIS). The most fragile areas of the cavities will be indicated, limiting the protection environments, in those places with risk of geological and archaeological effects. Our team is a pioneer in the recent publication of this type of actions aimed at protecting the underground cultural heritage.

In summary, through this project we propose to study the current and past dynamics of three caves in the Autonomous Community of the Basque Country (Santimamiñe and Lumentxa in Bizkaia, and Altxerri in Gipuzkoa), to prevent possible future alterations that could influence their conservation. By carrying out this work, it will be possible to design effective protection protocols for them, enforceable by the public administrations in charge of their safeguarding. In addition, these protocols will be extendable to all decorated cavities in the Basque Country, adding exclusive modifications for each site, and applicable both by the administrations at the community, provincial and local level.

The general objective of this study is to carry out an investigation that helps to guarantee the future protection of the decorated caves of the Basque Country. Two caves have been selected that have prior monitoring of their environmental parameters, Altxerri in Aia (Gipuzkoa) and Santimamiñe in Kortezubi (Bizkaia), both recognized as World Heritage by UNESCO; and the Lumentxa cave (Lekeitio, Bizkaia), classified as a Site of Cultural Interest, and in which it is intended to begin with an effective monitoring of its environmental parameters. To the studies of the determined environmental parameters (humidity, CO2 and temperature), the geological studies will be added that allow knowing and chronologically characterizing the sedimentation and erosion processes that occurred in the caves, in order to be able to form a stratigraphy related to the formation processes of the same. These studies will be carried out both at the macro level (in the entire cavity), and at the micro level (in the panels with rock art). The results obtained in these caves will allow predictive risk models for each case, and effective protection protocols will be designed that are applicable to other caves with rock art in the Basque Country. For the successful achievement of this general objective, a series of specific objectives (SO) have been set, always limited to the project’s performance time:

 

• SO1– Know the responses or dynamics that occurred in the selected caves (Lumentxa, Santimamiñe and Altxerri) to the global environmental changes of the past.
• SO2– Analyze the current dynamics of the three caves and, in relation to this, identify and characterize the pathologies that affect the conservation of rock art and geological formations.
• SO3– Predict the impact of future global changes on the cultural and geological heritage of these caves.