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Chapter 7 – The Conservation of Altamira Cave: a Comparative Perspective
p. 169-182
Texte intégral
1The problems of conservation affecting Altamira Cave and its paintings were summarized by Manuel Hoyos in 1994 in terms of three fundamental categories:
– the karst geological characteristics of the cave,
– the altered state of the paintings,
– the anthropogenic transformations outside and inside the cave, concerning the form, structure, microclimate and microbiology.
7.1 Protecting and consolidating the cave, a continuing concern
2Chronologically, these problems developed gradually over time. The initial preoccupation due to the cave’s geological fragility led to a series of large-scale structural consolidation and reinforcement works inside the cave. These works in the underground space modified the climatic conditions and, subsequently, the preservation conditions of the paintings. The enormous number of visitors contributed to aggravating the situation.
3Geologically, Altamira cave is in a phase where it is caving in, and is tending to disappear due to successive subsidence episodes. It was formed by gravitational collapses and not by hydric circulation (fig. 97).

FIG. 97 – Altamira Cave. Gravitational collapses occurring since prehistory in a karstic system in the process of collapsing.
© P. Saura / musée d’Altamira.
4A consolidation project was initiated in 1924 with two main goals: to facilitate public access to the site by laying out paths and installing electricity in the cave and to prevent further collapses (fig. 98). Walls and pillars were built to support the vaults and a large concrete and stone structure was built to divide the large entrance hall into two parts, separating the vestibule from the decorated zone (fig. 99). The Polychrome Ceiling was thus isolated in a very small space and subject to new environmental conditions that bear no resemblance to those that had allowed its conservation for thousands of years (fig. 100). The massive tourism activity amounted to more than 173,000 visitors for the year 1975, and worsened the conservation problems (fig. 101).

FIG. 98 – The inside of Altamira Cave was completely transformed to facilitate public access and prevent new collapses.
© Musée d’Altamira

FIG. 99 – Digital mapping of Altamira Cave: restitution of the current situation (left) and the original state (right).
© Information géographique propriété de l’Instituto geográfico nacional (Espagne).

FIG. 100 – Altamira Cave. Due to the modifications to the cave, the rock art has remained isolated within a limited space and has thus been subject to new climatic conditions.
© P. Saura / musée d’Altamira.

FIG. 101 – Visitors to Altamira Cave during the 1960’s.
© Musée d’Altamira.
7.1.1 1977-1997
5The Ministry of Culture acquired the cave in 1977. Its first measure was to close the cave and create a research committee that consulted the specialists already working at Lascaux.
6In 1979, the Altamira National Museum was created with the goal of managing, preserving, studying and promoting Altamira Cave. Hightechnology scientific equipment was purchased to preserve the paintings and the University of Santander was commissioned to conduct a study under the responsibility of Professor Eugenio Villar. The goal was to find a state of equilibrium in the ecosystem that would maintain the Hall of Polychromes with stable parameters while retaining the cave’s natural ventilation, with no installations of artificial climate regulation systems. The researchers developed a mathematical model that takes into account the outside climate and its seasonal variables, the underground climate itself and the heat generated by each visitor. They set a visiting rate that theoretically would not jeopardize the preservation of the cave, insofar as the disturbances induced were absorbed by the cave during its closed hours.
7Starting in 1982, a variable visiting rate according to the months of the year was established and maintained until 2002, in function of the mathematical model: in May the daily quota was 10 people a day, in June it rose to 40 people a day.
8Starting in 1993, the conservation-related research was entrusted to a single multidisciplinary team composed of researchers from the various institutes of the Spanish Council for Scientific Research (CSIC). There was therefore one working team that ensured the continuity of the research over time and the development of long-term goals and research plans. This team was coordinated until 1999 by Manuel Hoyos, and from 1999 to the present day by Sergio Sánchez-Moral, two researchers from the Museo Nacional de Ciencias Naturales in Madrid.
9In 1993, Hoyos reported the following alterations, which had historically affected Altamira Cave:
– millimetric exfoliations caused by temperature and humidity variations,
– the disappearance of pigments due to the humidity of the ceiling, and the erosion of the paintings by dissolution,
– the formation of limestone concretions or veils of calcite in zones where cracks facilitate the flow of water.
10The first signs of microbiological activity in the cave’s entrance area were also recorded at this time.
11Between 1997 and 1999, it became clear that the microbiological contamination was progressing gradually from the cave entrance towards the interior. Geochemical studies of the infiltration waters and the microbiology of the cave, revealed a great abundance of organic pollutants. They originated from the waste of the neighboring stock-breeding farms and the systematic spreading of manure on the meadowlands. Nitrites, more nitrates, phosphates… and other chemical substances arrived inside the cave dissolved in the infiltration waters, creating a rich substratum of nutriments for the growth of the microorganisms. Given the strong influence of the external ecosystem on the preservation of the cave and its paintings, it became necessary to eliminate or control these risk factors, both real and potential. To achieve this, a detailed document entitled Museological Plan for Altamira was drawn up concerning the preventive conservation of the cave and its environment. This plan, which was implemented between 1997 and 2001, estimated the risks and established management measures designed to ensure the complete protection of the environment.
7.1.2 1997-2001: the Museological Plan for Altamira
12The key points of the museological plan for the preservation of Altamira consisted of local development plans and preventive conservation of the environment surrounding the cave. The following operations have been carried out:
13– 120,000 m2 of land were acquired to extend the absolute protection zone vertical to and surrounding the cave; the property of the Altamira museum was increased to 180,000 m2, making it possible to intervene directly to avoid the risks related to its farming, stock-breeding and residential usage, and to create a maximum protection zone; it was also possible to eliminate infrastructures and services and to restore the original landscape environment;
– three houses and their respective stock-breeding facilities were removed and placed in another part of the district in order to eliminate the environmental risks;
– the parking lot and water and electricity supply structures were removed;
– one of the old museum’s pavilions was demolished because it was close to the cave and built on the same geological stratum as the vault of the cave;
– the path that passed directly above the cave was eliminated and a new road was built further away to avoid pollution and vibrations;
– a new building and parking lot were built outside of the cave’s rain catchment area;
– new conservation studies by CSIC were commissioned;
– the natural relief and landscape in the immediate vicinity of the cave were restored to their original appearance;
– a protected environmental zone was created following the current regulations concerning the urban development plans for the two districts in which the cave is located, accompanied by utilization restrictions over vast areas.
14Everything leads us to believe that these preventive conservation operations have made it possible to control the catchment area and the cave itself. The museological plan has played a role in confronting the probable risks and known dangers (fig. 102).

FIG. 102 – The landscape immediately surrounding the cave after the realization of the Museographic Plan for Altamira.
© Manuel Bahillo Martín.
7.1.3 2002-2005
15For various reasons the cave had to be closed to the public again in 2002:
– twenty years had elapsed since the above-mentioned visiting restrictions had been put in place, and their impact on the cave had to be assessed;
– there was a clear increase in the microbiological activity in the cave;
– green spots, due to random failures in the lighting system, had been detected on the Ceiling of Polychromes;
– the effects of climate change had to be assessed.
16This decision was influenced by the information that we received from our colleagues at Lascaux concerning the sudden and massive development of fungi, recommending a drastic preventive policy, such as closure of the cave.
17This was done in September 2002. The first measures adopted were the total elimination of electric lighting inside the cave and the intensification of conservation studies. A new cooperation agreement between the Ministry of Culture and the CSIC (attached to the Ministry of Sciences and Innovation) was signed in order to accomplish a meticulous study of the condition of the cave and its paintings.
7.2 Natural Sciences in Altamira Cave
18Since 2003, it has been possible to conduct research under virtually natural conditions, without the disruption caused by visits. It has thus been possible to characterize the underground physicochemical system and to create an integrated model of how it functions. The CSIC team has been working on four key areas of research since 2003: internal microclimate, hydrogeochemistry, outdoor edaphic cover and microbiology.
7.2.1 Internal microclimate
19In terms of the internal microclimate, Altamira is a system with a dynamic and fragile equilibrium. It has a stable micro-atmosphere due to its low rate of energy exchange with the exterior and its low rate of infiltration; these are precisely the reasons why the cave paintings were in good condition when they were discovered (fig. 103a-b).

FIG. 103 – The climatic control equipment in Altamira Cave: a, b in the Hall of Polychromes; c outside.
© CSIC.
20During the time the cave was open to the public, the visitors caused a daily increase in CO2, water vapor and air temperature, in an atmosphere that was already saturated. These variations favored the development of micro-corrosion processes on the stone support of the paintings and activated the metabolic processes of the microorganisms that were colonizing the stone.
21Since its closing in 2002, we have observed a greater physicochemical stability in the cave because the average temperature of the air, and the minimum temperature in particular, have decreased. These data indicate that the climatic model and visiting rates applied between 1982 and 2002 were the origin of a certain accumulated disruption. In addition, the microbiological colonization increased gradually and advanced over time towards the interior of the cave. In 2007, an airlock was installed between Hall of Polychromes and the vestibule area to serve as a second barrier to prevent the exchanges of matter with the outside.
7.2.2 Hydrogeochemistry
22The role of water in the physicochemical system of the underground atmosphere is fundamental: it absorbs and transports the CO2 and the soil’s chemical elements, causes the partial dissolution of the stone and fills part of the soil and stone’s porous systems, promoting an accumulation of gas inside.
23We perform a seasonal verification of the water’s physicochemical characteristics (temperature, pH, levels of dissolved CO2 and of dissolved organic matter) and of all the elements that could serve as nutriments for the microbial communities present inside the cave.
7.2.3 External soil
24The exterior edaphic cover plays an essential role as a source of CO2, organic matter and fundamental nutriments for the development of microorganisms inside the cave (fig. 103c).
25Until 2000, stock-breeding activities enriched the soil with nitrogencontaining compounds. The organic matter present in the exterior soil had for years represented an additional source of nutriments for the microbial communities. One of the measures adopted was the control of the external vegetation by removing certain areas of shrubs and monitoring the growth rate of grasses. This has given positive results that have been materialized by a reduction in the nitrate levels in the infiltration waters.
26Overall, the karst system has been found to be highly sensitive, in physicochemical terms, to any modifications that occur in the outdoor soil. At present, we are working on the delimitation of the total protection zone of Altamira Cave and of the rain catchment area through a new detailed geomorphological study combined with the use of geographic information systems.
7.2.4 Microbiology
27The walls and ceiling of the cave show signs of a bacterial colonization that appear as spots, usually round, which may group together and create irregularly shaped patterns, colored white, yellow and gray (fig. 104). These colonies are present from the entrance until the Hall of Polychromes, and they are distributed in zones according to the microclimatic conditions:
– the yellow colonies are mainly found in the areas close to the entrance, where there is a greater variability in temperature and relative humidity;
– the grey colonies are mostly present at the junction between the access gallery to the Polychromes and the gallery leading to the Hall of Walls;
– the white colonies are distributed throughout the cave, from the entrance to the Hall of Polychromes, and are the only ones present in this chamber.

FIG. 104 – The climatic control equipment in Altamira Cave: a, b in the Hall of Polychromes; c outside.
© CSIC.
28These colonies are composed of a wide variety of species, forming a bacterial film that covers the walls of the cave. Many of the bacteria that we are currently isolating constitute species that are new for science (Jurado et al. 2006; 2008a; 2008b). The presence or growth of fungi on the walls and ceilings that are colonized by bacteria has not been observed, which leads us to think that the bacteria may prevent, in some way, the germination of fungi spores, due to anti-fungal substances. Recently, we have found a few hyphae suspended from the ceiling, with a maximum length of 2 cm, which are removed periodically at the time of maintenance work, and which correspond to the germination of some fungal spores in the cracks in the ceiling.
29In the Hall of Walls (hall IV) only, in the interior part of the cave, we observe colonies of fungal hyphae whose appearance suggests that they appeared due to the multiplication of Basidiomycetes. Wood was used in the construction of these walls (1950-1960) and these fungi developed from this wood. At present, these hyphae are for the most part calcified. It has not been possible to demonstrate any increase in their number or their activity in specimens taken after incubation in the laboratory.
30Bacteria and fungi exist in Lascaux Cave. The colonies of fungi are distributed throughout the cave in the form of colonies or filaments of white hyphae, attributed to Fusarium solani, and in the last few years, in the form of black spots that have been attributed to the development of melanin-pigmented fungi (Bastian, Alabouvette 2009).
31No biocide products have ever been used in Altamira to eliminate the populations of microorganisms, and it seems that the fungi are not capable of colonizing the walls and vaults already covered with microbial films of bacteria. This finding allows us to propose the hypothesis that the use of benzalkonium chloride at Lascaux may have led to the elimination of the natural colonies of bacteria that could have an antifungal activity, and to the selection of other bacteria which do not seem to have the ability to inhibit the growth of fungi, perhaps making it possible for fungi to appear on the walls (Bastian et al. 2009a; 2009b).
32The result obtained from a test performed in 2007 at Altamira to understand the stone colonization mechanisms seems to support this hypothesis. The fungi quickly covered different types of limestone introduced into Altamira Cave that had not been colonized beforehand by the cave’s own bacteria.
33In 2007 and 2008, inside the cave we observed an increase in the number of certain insects acting as carriers of entomopathogenic fungi. These were caddisflies that live on riverbanks and take shelter in the cave looking for humidity. All this encourages us to strengthen our monitoring of the cave (Jurado et al. 2008b; Bastian et al. 2009b). We are currently considering installing a system of millimetric nets in front of the entrance to the cave to prevent the insects, which systematically appear in April and throughout the summer, from entering.
7.3 Conclusion
34Altamira has benefited from the experience gained at Lascaux because it has encountered problems with a certain delay. This explains why we rejected the idea of installing an air conditioning system and why we have currently decided not to use biocide substances to combat the bacteria present. We opted for preventive conservation implying actions tending towards the non-introduction of disrupting elements and for exhaustive monitoring making it possible to detect evidence of any deviation from the cave’s environmental conditions, so that we can act appropriately and in time.
35In October 2009, the cooperation agreement between the Ministry of Culture and CSIC for the study of the conservation of the cave and its paintings came to an end. Its main contributions are:
– the implementation of a system of monitoring and continuous and permanent assessment of the main environmental parameters, defining risk and alert thresholds or symptoms and the corresponding intervention protocol in each case;
– the integration and spatial visualization of all the data obtained, allowing the possibility of drawing conclusions concerning the conditions that are favorable and/or unfavorable for microbial proliferation and, consequently, of taking corrective measures to arrest its development;
– the definition of the geospatial and microclimatic conditions that are favorable and/or unfavorable for the development and growth of microorganisms with a view to limiting their proliferation. To achieve this, we drew up an integrated model with all the microbiological, lithological, mineralogical, geochemical, petro-physical and microclimatic data making it possible, at a later time, to design and apply specific corrective measures.
36The CSIC (attached to the Ministry of Sciences and Innovation) was entrusted with the natural sciences research concerning the cave and its paintings; it is now the task of the Ministry of Culture to apply the acquired scientific knowledge to the conservation and management of the World Heritage Site that is Altamira Cave.
37References
38Bastian, Alabouvette 2009 : BASTIAN (F.), ALABOUVETTE (C.). — Lights and shadows on the conservation of a rock art cave : the case of Lascaux cave. International journal of speleology, 38, 1, 2009, p. 55‑60.
39Bastian et al. 2009a : BASTIAN (F.), ALABOUVETTE (C.), SÁIZ‑JIMÉNEZ (C.). — Bacteria and free‑living amoeba in Lascaux cave. Research in microbiology, 160, 1, 2009, p. 38‑40.
40Bastian et al. 2009b : BASTIAN (F.), ALABOUVETTE (C.), SÁIZ‑JIMÉNEZ (C.). — The impact of arthropods on fungal community structure in Lascaux cave. Journal of applied microbiology, 106, 5, 2009, p. 1456‑1462.
41Cuezva et al. 2009 : CUEZVA (S.), SÁNCHEZ‑MORAL (S.), SÁIZ‑JIMÉNEZ (C.), CAÑAVERAS (J.C.). — Microbial communities and associated mineral fabrics in Altamira cave, Spain. International journal of speleology, 38, 1, 2009, p. 83‑92.
42Jurado et al. 2006 : JURADO (V.), GONZALEZ (J.M.), LAIZ (L.), SÁIZ‑JIMÉNEZ (C.). — Aurantimonas altamirensis sp. nov. : a member of the order Rhizobiales isolated from Altamira cave. International journal of systematic and evolutionary microbiology, 56, 11, 2006, p. 2583‑2585.
43Jurado et al. 2008a : JURADO (V.), BOIRON (P.), KROPPENSTEDT (R.M.), LAURENT (F.), COUBLE (A.), LAIZ (L.) KLENK (H.P), GONZÁLEZ (J.M.), SÁIZJIMÉNEZ (C.), MOUNIÉE (D.), BERGERON (E.), RODRÍGUEZ‑NAVA (V.). — Nocardia altamirensis sp. nov., isolated from Altamira cave, Cantabria, Spain. International journal of systematic and evolutionary microbiology, 58, 9, 2008, p. 2210‑2214.
44Jurado et al. 2008b : JURADO (V.), SÁNCHEZ‑MORAL (S.), SÁIZ‑JIMÉNEZ (C.). — Entomogenous fungi and the conservation of the cultural heritage : a review. International biodeterioration and biodegradation, 62, 4, 2008, p. 325‑330.
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Lascaux et la conservation en milieu souterrain
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