Diquís stone spheres undergo a conservation process-Since last March 2, 2020 and until next Friday 20, two of the five pre-Columbian stone spheres, located in the Museo Sitio de Finca 6, located in Palmar Sur de Osa, are subjected to conservation-restoration interventions aimed at optimizing their stabilization and reading, through professional methodologies of archaeological preservation, as reported by the National Museum of Costa Rica (MNCR).
The work runs until March 27, by monitoring the work carried out in 2019 in the monumental area of the El Silencio archaeological site, as well as monitoring the adjacent cobblestone segment that was also intervened in 2019.
Both the Museo Sitio Finca 6 and El Silencio are part of the Cacical Settlements with Diquís Stone Spheres, declared World Heritage in 2014.
After two seasons of on-site work (2017-2018), dedicated to documentation and diagnosis, which included the systematic recording of rock characteristics (color, hardness and moisture absorption), of its physical-mechanical, physical- chemical, biological and anthropic (human activity), as well as the monitoring of temperature and environmental and superficial humidity, it was determined that these sculptural monuments required direct intervention to stabilize certain vulnerable sectors.
These are the spheres that archaeologists call A and E, which are part of the only two alignments of stone spheres in situ, preserved so far in the Diquís, southeast of Costa Rica. These monuments have between 1.75 and 1.58 meters in diameter, respectively.
The direct and indirect conservation of Spheres A and E of Finca 6 represents its most forceful treatment; In the coming years, the work will focus on monitoring and maintenance actions in periods of greater temporality. In addition, intervention will begin in other areas of the alignments.
Works in the spheres at the Finca 6 archaeological site In this 2020 season, the interdisciplinary team made up of specialists from the National Museum of Costa Rica (MNCR) and the National School of Conservation, Restoration and Museography (INAH, Mexico), united by a cooperation agreement between both countries, focus on the conservation and restoration of these two areas of the Finca 6 site, one for each alignment oriented east-west.
MNCR data indicate that the need to intervene in these spheres is due to the degradation and constant loss of the rocky material that composes it, especially in sphere E, whose crown (exposed part) has a significant shortage. Scientific studies carried out by Dr. Manuel Espinosa Pesqueira (Institute of Aesthetic Research, UNAM, Mexico), determined that the composition of the rock with which it was carved leads to intrinsic alterations, since “its composition of silica, alumisilicates and carbonates contain montmorillonite clays that favor disintegration, ”explained Dr. Isabel Medina González of the National School of Conservation, Restoration and Museography INAH, Mexico.
The conservation-restoration work in the two spheres of Finca 6 consists of unearthing them, carrying out photographic documentation at the beginning of the process and subsequently carrying out direct interventions. First, a non-abrasive cleaning is performed both dry and wet on the surfaces.
Subsequently, consolidation tasks are carried out, applying edging and protective reams made with lime and sand-based mortars, which allows the progress of certain alterations to be stopped, especially the crown, which is the part that will be exposed. “Our intention is to protect them, always preserving the unique and exceptional values, as well as the integrity and authenticity that make them relevant and significant as a pre-Columbian legacy of the ancient populations of the Diquís. For this, it is necessary to preserve the marks of time that make evident the hundreds of years that they are old, “added Dr. Medina-González.
The reams and trims are finally worked on the surface with colored paste mortars and chromatic reintegration with natural pigments to favor their reading, Medina-González explained.
The archaeologist, MsC. Javier Fallas of the Department of Protection of Cultural Heritage of the MNCR, explained that the spheres are intervened with materials compatible with the mineralogical composition of the rock with which the spheres were made. “Thanks to the tests carried out in 2017 and 2018, and their periodic monitoring, we know that the mixture of lime and sand is the most suitable for intervening these monuments; the proportions for each of the spheres is determined according to the composition of the rock, the information of which is based on scientific studies, ”added the specialist.
Once the process of direct intervention of the spheres is completed, some preventive conservation measures will be taken to favor the preservation of the monoliths. Dr. Medina added that “it is necessary to re-bury them, as leaving them fully exposed could accelerate the alteration processes that would irreversibly damage them.” Re-burial is an internationally accepted technique to promote the preservation of archaeological assets in situ; In the case of Finca 6 spheres, this process consists of replacing clayey sediment with inert sand, a process that has proven to be successful in controlling humidity and acidity in the deposit, as well as controlling micro- flora and higher plants on the surface.
Archaeological investigations carried out by the Department of Anthropology of the MNCR, have determined that the stone spheres of the Finca 6 archaeological site date back more than 1000 years.
As a curious fact, specialists conclude that the five stone spheres that make up the only two alignments in situ at Finca 6, are representative of the variability of rocky materials with which most of the identified stone spheres in the region are made.
Monitoring of the El Silencio site After, in 2019, the sphere and the paving of the El Silencio archaeological site underwent a conservation-restoration process, in this 2020, the team of restorers returns to monitor both the sphere and the cobblestone associated with it.
Through photographic records, the behavior of the interventions carried out in 2019 will be assessed. In the case of the monumental sphere, some maintenance actions will be carried out, including optimization and chromatic reintegration of the areas intervened in 2019. On the other hand, Monitoring and maintenance measures will be carried out on the mortars used in the exposed sector of the paving, explained the MNCR archaeologist, Javier Fallas.
“Monitoring and maintenance are fundamental strategies in the care of the archaeological heritage already intervened, since they ensure its preservation in the short, medium and long term,” added Fallas.