- Can I come closer to see the chains?
Shyly, a neighbor from Obligado, about 185 kilometers north of Buenos Aires, asks the team of archaeologists from the University of Luján, which measures and analyzes 14 iron links anchored to the ground on the banks of the Paraná. The largest river in Argentina is at its lowest level in the last 50 years and the retreat of the waters led a fisherman to find these chains in early August. All the indications suggest that they are part of the defensive system against the Anglo-French fleet that in 1845 sought to impose by force free river trade, prohibited to foreigners by the Government of Juan Manuel de Rosas. In a few days, in the middle of the covid-19 pandemic, a campaign has been organized to investigate the finding, witnessed by EL PAÍS.
On November 20, 1845, the fleet - made up of a hundred merchant ships, guarded by warships - was stopped by three rows of wrought iron chains that crossed the Paraná from coast to coast mounted on 24 barges. As they worked to break through the defense devised by General Lucio Mansilla, the confrontation began. First, with artillery crossfire and when disembarking, melee.
Vuelta de Obligado was the first battlefield excavated in Argentina. For two decades, an interdisciplinary research team led by Mariano Ramos has traced the traces of that combat recreated on 20-peso bills and on the date of which the National Sovereignty Day is commemorated. “The chains are a symbol of the sovereignty of a country that stands before two powers like England and France. They wanted to block the unpunished path they wanted, "says Ramos for Zoom.
For prevention against the coronavirus, Ramos does not participate in the campaign in Obligado, but he is glued to the phone to know at all times how they are progressing. This Monday, when resuming the work that began last week, archaeologists excavate around the chains, which are right on the shore. They sink inland, to a still unknown depth, and are contained by a large layer of tosca - calcareous rock - that makes their extraction difficult.
“Our objective is not to remove the chain, but to learn from it. Where is it, when it measures each link and how much they measured, according to Lucio Mansilla, which is similar if one takes into account that there is loss of material. If someone takes it, it is as if I grabbed a history book and tear out ten pages, ”describes Carlos Landa, a researcher at Conicet.
Travel reduced by the pandemic
The covid-19 pandemic forced the suspension of the planned campaign in April, but the discovery of the chains and the fact that they can only be studied while the historical downspout of the river lasts allowed obtaining permits for two reduced expeditions. Of the twenty people who usually work, less than half have traveled. Instead of staying on the ground for a few weeks, they are brief two-day outings.
Landa reduces the water that enters the well while her colleague Alejandra Raies measures link by link and sings the numbers to Daniel Gómez, who writes them down in a notebook. Carolina Leiva records the entire process with a camera, Alejandro Ravazzola records it and Jerónimo Angueyra performs a photogrammetry with drones.
"We have to wait for the results of the laboratory analyzes, it will take a few months, but expectations are high," says Landa about the possibility that it is the chains of battle. Universities are closed due to the pandemic, forcing complex tests such as electronic scanning to be postponed, but a preliminary analysis shows that the links were made before 1845. Their location also coincides with the defense plan drawn up by the captain and cartographer English Sullivan. "By geographical position it is the first time that a chain appears in context, with original position and both by appreciation at a glance and by the metallography that the engineer Horacio de Rosa gave us," says Raies. The key is the stud, a crossbar located in the middle of the links that prevented the chain from collapsing. According to De Rosa's analysis, the link is forged and the stud was heated red-hot and hammered in, a technique used in the first half of the 19th century.
As they speak, three dogs chase a sow along a nearly empty shoreline and a deep-draft Chinese vessel descends the Paraná, possibly laden with soybeans, Argentina's main source of foreign exchange. The downspout of the river that favors archaeologists, on the other hand, complicates navigation and the extinction of fires caused in the islands of the delta. The smoke reaches Obligado and over time irritates the eyes and throat.
"It's very exciting. I wanted to come with the boys, it's not the same as studying it at school ”, says a neighbor who has pedaled with his two children to the beach. The three watch as the team draws a 100-meter line with stakes from the chains towards the promontory drawn on Sullivan's cartography, where the Argentine defensive system was fixed. They survey every ten meters and scan the area with a metal detector, digging every time it rings. They dig up hooks, nails and cigarette paper. "The results were negative, but that is information for us, because we know that it is a space that we do not have to address again," says Landa.
A day later, the dug wells will disappear: the Municipality is filling the area with earth to create a river beach with which to attract tourism once the quarantine restrictions are lifted. The chains will remain in the custody of the Prefecture. “The archaeologist has to do a work of heritage awareness on the population. You are a researcher of the nation, there is a heritage law, but you work with the community, which has its imagination. When you think that archeology is excavating and not dealing with people, you are wrong, it is an anthropological work ”, the researcher emphasizes.
Waters without visibility
The team also planned to dive off the coast to search the water for a possible exit from the chains, but the Prefecture prohibited them from diving with a tank. Still, the underwater archeology specialist Amaru Argüeso inspects the area with brief dives in apnea. “What I identified is that up to eight, nine meters deep, there is like a ravine in decline with a very soft clay silt. We tried a 1.40 rod to bury it and it kept going. That tells us that it has a very high burial potential, so it is unlikely to be able to find the chain by touch, ”says Argüeso when emerging from that earth-colored river.
The zero visibility of the Paraná waters - which forces you to dive to the touch -, its depth greater than 40 meters, the strong current and the traffic of boats have made it impossible for now an underwater campaign to try to check if the anomalies detected in a swept in 2016 belong or not to the defensive system disrupted by the Anglo-French fleet.
Mansilla chose Obligado because of the defensive potential of its ravines and because of the meander of the Paraná in the place, which forces navigation to slow down. The Europeans, far superior in weapons and training, defeated the Argentine forces, but the trip to trade in the river was considered a failure and shortly after they gave up their objective.
On Tuesday, the water has risen a foot and covers the chains that were visible the day before. Part of the team crosses with a fisherman the 700 meters of Paraná to the other coast to track down three points marked in advance and make a sweep with the metal detector that also gives negative. In the afternoon, they track the river with a magnet and the boat loaned by another fisherman.
Ramos confirms that they would like to know the extension of the chains found and the type of fixation, but they do not plan to remove them from the place, beyond the link extracted as a sample. "We want them to be preserved in place and to mark them in some way," he anticipates. The chains will be underwater again, but their story will stay afloat.