The effects of exploiting a quarry for five thousand years

Researchers have scientifically described an ancient open-pit mine in the Buenos Aires area of ​​Argentina that, over 5,000 years of exploitation, markedly altered the landscape.

The study is the work of a team that includes researchers from the National Scientific and Technical Research Council (CONICET) who are part of the group from the Archaeology and Anthropology Area of ​​the Museum of Natural Sciences of Necochea, in the province of Buenos Aires, Argentina, all of these entities.

The study was carried out at the archaeological site of El Picadero, located in the district of Tandil, where ancient hunter-gatherer societies were dedicated to the intensive extraction of stone materials. The large amount of waste produced by the carving and the earth removed in uninterrupted excavations generated a unique landscape of pits and “hills” of stone waste.

The research reveals a dynamic of uninterrupted exploitation of this ancient mine, unprecedented in the country. These ancient hunter-gatherers of the Pampas region exploited the aforementioned quarry or open-pit mine in the area of ​​El Picadero for 5,000 years, until the arrival of the Spanish.

“Although it was already known that the area had been visited by hunter-gatherer societies to exploit its raw materials for thousands of years, it was surprising to find places where people organized such intensive tasks of extraction and processing of rocks,” Mariano Colombo, a doctor in Anthropology, and Celeste Weitzel, a doctor in Archaeology, explained to the CyTA-Leloir Agency.

“These are the first records that describe such a marked human modification of the landscape. They also indicate the existence of very specific techniques, tools, uses of the body and learning in relation to the tasks of quarries, as well as long stays in the places and a very strong practical and symbolic connection between people and the quarries and mountain spaces,” they added.

The work was presented in Comechingonia, Revista de Arqueología, a prominent scientific publication with more than 40 years of experience, linked to the National University of Córdoba (UNC) in Argentina.

The research was carried out in a rural area about 55 kilometers south of the city of Tandil. (Photo: Necochea Natural Sciences Museum / CONICET / CyTA-Leloir Agency)

There are records of ancient inhabitants around the world who carried out very complex quarrying and mining tasks, both in the open air and in the form of underground galleries, mainly in Europe. In the American continent there are cases of more than 10,000 years of antiquity in which rocks were used that due to their characteristics would have been very special, such as obsidian (also known as “volcanic glass”), Colombo pointed out. In Argentina, to date, the only sites where rocks were obtained that show a similar intensity are the 13 that were found in the centre of the Tandilia system.

But El Picadero has unique characteristics due to the magnitude, length of time and complexity of the extraction tasks, which began by collecting rocks from the surface and continued with the excavation of galleries. This gave rise to immense piles of stone waste, whose dimensions exceed 3,000 square meters in different areas of the slopes or peaks of the hills.

“The data indicate that excavation activities to extract rocks were carried out at least since the middle Holocene [7.500 a 4.500 años atrás]at which time the quarry landscape was already completely modified, with extraction pits 1.25 metres deep compared to the current ground and at least 1.65 metres from the original surface and, therefore, generating an alteration of the terrain with much more marked undulations than those observed today,” explain Colombo and Weitzel.

The main raw material sought in El Picadero and in the region was orthoquartzite, used by hunter-gatherer peoples to make tools for everyday tasks such as cutting plants and meat, making clothes, coats, shelters or hunting weapons, Weitzel said. However, due to their qualities (colour, shine) these rocks would also have had an aesthetic and symbolic “added value”, which justified their repeated and intensive extraction over millennia.

The modification of the landscape produced “does not appear, so far, to be the cause of any change or modification that impacted the hunter-gatherer way of life. Rather –the research team concluded– it seems to indicate the very intensive use of a vital resource with a very particular symbolic and aesthetic importance. This was the case until the time of the European conquest of the territories, a stage in which the Pampas hunter-gatherer societies had increased their networks of social interaction as they became more numerous, territorial and sedentary.” (Source: CyTA-Leloir Agency)