The Bali Aiki volcanic field is located in the far south of the Patagonian desert, on the border between the province of Santa Cruz and the Chilean region of Magallanes, a few kilometers from the strait of the same name. A challenging landscape, it is difficult to imagine in present-day eyes what life was like for the people who traveled across it thousands of years ago in search of food and shelter. But archeology, especially the study of rock art, provides knowledge about the daily life of these nomadic societies in the past, by investigating marks captured in caves, friezes and walls. The analysis focuses on both the shape, size and distribution in space of these representations, as well as the age and composition of the pigment mixtures.
Recent work published in the Journal of Archaeological Science: ReportsTwo researchers from CONICET have revealed unknown and new aspects about the rock representations found in southern Santa Cruz. At the Romario Baria friezes, located in the Gallegos River Basin, scientists have obtained the first direct radiocarbon dating of cave paintings in southern Patagonia by AMS. Studies have shown that these representations are more than 3,100 years old, while they were thought to be at most 2,000 years old. It was also possible to establish a chronological order in the use of colors (red, white and black) and to determine the composition of the dye mixtures used.
As the scientists conclude in the published work, these results provide the first history of photographic activities in the Pali Aik volcanic field, assigned to the so-called Rio Chico style, extending from ancient times to about 1,000 years ago.
The Rio Chico style is a style of geometric shapes made using linear strokes and the dominant color is red, in which more than 90 percent of the representations are made. Black and white are a minority.
“What radiocarbon dating conducted by Alejandro Cherkinsky, a researcher at the Center for Applied Isotope Studies at the University of Georgia (USA), has shown, is that red was the color most commonly used as early as 3120 ± 60 years ago (before present). Red has been in use for thousands of years. Black, on the other hand, came into use during the last 760 years BC, which is why decorations in this color have become less common. “However, it is necessary to conduct further dating to confirm this,” explains Judith Charlin. At the same time, he regrets that “the white paint sample did not contain There is enough organic material to date it, so we have no absolute chronology of the use of that color, although we assume it was before black, as indicated by the compositions of black on white decorations.
This pictorial activity is associated with an increased density of site occupation in the region over the last 3,500 years. The various pictorial events suggested by the overlay of ornaments, color variations and direct chronologies obtained at Romario Baria indicate prolonged and repeated use of the site.
In general, rock representations of the Pali Aik volcanic field are found in sectors of the landscape that do not strictly relate to habitation sites, as for example at Cueva de la Manos northwest of Santa Cruz, but served as markers in the landscape of resource supply areas , such as sources of rocks used in the manufacture of stone artifacts, or large lakes and riverbeds, where animals are concentrated: guanacos, thorns, or other types of birds. “The sites with megalithic representations that we study are generally associated with roads or trading sectors. Studying their location in physical terms, through geographic information systems (GIS), shows that these sites are not associated with places where there is a great abundance and diversity of archaeological remains.
Techniques and materials used
Scientists conclude that fingers were used to create most of the paintings studied, and it also indicates the presence of phalangeal features in other archaeological sites in the region.
“In terms of techniques, we know that fingers were used and also a type of brush that could have been made from plant remains, guanaco or human hair. Although there is no evidence in this regard, and we know very little, we can tell the differences In showing the strokes when they are with fingers and when they are with a brush. But this is something that we evaluate based on how the paint disperses. We analyze fingerprints, which are called eudermatoglyphs, which is something innovative for our country. We do it with people who specialize in criminology. We have gone into the field “To take fingerprints on cave paintings to identify the gender and age of the painters.”
Regarding the materials used, analyzes of the composition of red paints – conducted with a technique called Raman spectroscopy – indicated that the most widely used pigment in time and place is hematite, and it comes from the volcanic outcrops of the Sahara. region. Basalt, which changes due to weathering, the process of changing the color, texture, composition, or hardness of rocks and minerals from the action of water or the environment, produces hematite. Thus, scholars can also conclude that the raw materials needed to make the paintings were obtained locally.
“To obtain the samples that we dated, we scraped the surface of the paintings in a very small section so as not to damage the preservation of this evidence. We have ongoing analysis by X-ray diffraction at UBA's School of Exact and Natural Sciences to determine the composition of black and white pigments. At the moment, what we know about the black is that it does not appear to be made of carbon, but of manganese oxide, and the white of carbonate. But these analyzes are ongoing and we do not have results yet. “What has been accomplished in the region before is extremely rare.”
Finally, scientists point out that radiocarbon dating was possible because in the pigment mixtures, in addition to the use of minerals that gave the paints their color, other organic substances were added, called “binders”, because they allow them to give cohesion. For mixture of dyes. These appear to have been plant remains, according to certain indications, but there is also evidence elsewhere of the use of crushed or crushed animal bones. “On the central plateau of Santa Cruz, there is also talk of the use of tissues and fats from herbivores (most likely guanacos) and (white) albumen from coke or thistle eggs. So what has been dated about these paintings is precisely the organic part of their composition.
Much more than art
Some time ago, the field of archeology stopped referring to cave paintings, friezes, and walls as “rock art.”
“All this art is very much discussed, we talk about rock representations, and we all agree with that, but often for the sake of simplicity, and sometimes also because of tradition, we continue to talk about rock art. But it is a name that is no longer used. In fact, it is not We think it is art, if we consider it something that has no function other than aesthetic in itself. “We realize that rock representations perform many functions (social, economic, symbolic), and very important ones, in the context of the life of hunter-gatherers or other social groups,” Charlene explains.
(Source: IPCSH, CONICET).