The Columbian stone spheres are perfectly round and solid, but have eternal life. Hundreds of years of weathering under adverse weather conditions and the irresponsible actions of humans (such as deforestation or burning), are damaging these “old stones” made by our ancestors of the current borucas from 400 B. C. to 1,500 B. C.
The restorative and conservative Italian Emiliano Antonelli is visiting Costa Rica to diagnose the state of health of the stone spheres as a complement to conservation work that performs for 10 years the National Museum.
This evaluation is indispensable for the record that Costa Rica is preparing to apply for the areas as part of the World Heritage list of UNESCO.
“Mr. Antonelli presented to experts from the National Museum a report with an analysis of the situation and recommendations. The document will be analyzed to define a strategy for the conservation of these pieces, “said the director of the National Museum, Christian Kandler.
During the previous week, Antonelli analyzed 34 fields located in several archaeological sites in the canton of Osa, Puntarenas, from where they originate. The expert visited Villa 6, Villa 4, Batambal, and Grijalva, accompanied by a team of archaeologists and conservators from the National Museum, and the sculptor Jorge Jiménez Deredia, who is one of the main supporters of the candidacy of the spheres to Unesco.
Both Antonelli as the restorer Ana Eduarte agree that the main enemies of the areas are environmental and human biological.
One of the main damage is exfoliation present, this means that their “skin” is peeling stone layered like an onion. The appearance of an area that has suffered is like peeling skin “escarapelada”. Furthermore, deformed and loses its spherical appearance.
“The spheres are subjected to extreme temperature contrasts. We made measurements and at noon the stone surface can reach temperatures up to 50 ° C, while the nights can drop to 15 ° C. This causes cracks and landslides reventaduras “said Eduarte.
The high concentration of moisture is one of the main enemies of the spheres. “The strong and constant rains directly receiving and moisture that accumulates in the soil as a result of the flooding, creates optimal conditions for small ecosystems that develop on the surface or below,” he added.
In this way explained Eduarte, colonies of fungi, lichens and bacteria begin to form what is known as a biofilm that, at first glance, is a black crust or red or white patches covering the spheres.
Antonelli said, that threatens biofilm aesthetic characteristics of the area for hidden details of their textures, their manufacturing and even the signs inscribed in stone.