A drought in Spain has revealed an ancient stone circle that usually stands hidden beneath the waters of the Valdecañas Reservoir in western Spain. But the so-called "Spanish Stonehenge" is just a small piece of an ancient Spanish landscape flooded by dam construction in the 1960s.
The dolmen of Guadalperal
The exposed rocky floor of the reservoir today is punctuated by about 150 granite stones in concentric oval rings around a chamber about 5m wide, meant to enter through a megalith-lined passage facing east. It has earned the nickname "Spanish Stonehenge," but just something of a misnomer. Unlike Stonehenge, Guadalperal is built as an open-air monument.
The standing stones visible today are the framework of a burial mound. Once, the spaces between the concentric rings would have been filled with earth and pebbles, and the vertical stones would have supported a horizontal roof slab. An earthen mound would have covered the whole thing; you can still see the remains of that structure in the sand bank and the gravel that now surrounds the standing stones.
At the inner end of the passage, marking the entrance to the main chamber, one standing stone, or manhir, bears the carved image of a snake and several cups. Alcalá University archaeologists Primitiva Bueno Ramirez described the stone as “engraved showing a human body with bound shoulders and a severed head. On one side of the body, [there is] a sinuous line with a triangular head, which could be described as a snake. ”Very similar images have been found engraved or painted at the entrances of other dolmen in Spain, and the direction of the passage means that morning sunlight would help illuminate the image. .
Archaeologists have documented more than 400 similar monuments in Spain, mostly along the routes of the Tagus and Douro Rivers. They are usually associated with the remains of the earliest farming settlements in Spain, and burials in the dolmens often include artifacts from the Bell Beaker culture. The culture first turned up in Spain about 4,750 years ago and spread throughout Central and Western Europe and Northwest Africa by about 4,500 years ago.
A missing body
No human remains have turned at Guadalperal. When archaeologist Hugo Obermaier excavated the site in the 1920s, he found polished tools, flint, and pottery — the typical set of artifacts for a megalithic site, many of which were characteristic of Bell Beaker culture — but no people.
"But we have data on excavations in nearby megaliths very close to the Guadalperal, such as Azután, in Toledo, with an almost identical architecture where human remains were detected," Ramirez told Ars. Radiocarbon archaeologists have dated the remains of people buried in the dunes at Azután, and because Azután's construction is nearly identical to Guadalperal, Ramirez suggests that they are of similar age: somewhere between 5,000 and 6,000 years old.
But the stones themselves may have been quarried much earlier. Ancient people often moved menhirs from older tombs, often with their own graves, with occupants reburied in the newer dolmen. "There is evidence that older men are used as the initial components of many dolmens," wrote Ramirez and her colleagues in a 2015 book, The Megalithic Architecture of Europe.
Spain's drowned past
A nearby Roman settlement, the city of Augostóbriga, also lies submerged by the reservoir. It is likely that local people still used the monument while the Romans occupied the area. "Other Iberian and European megalithic funerary monuments show or use rituals of dolmens in Roman times," Ramirez told Ars, though she added that there was no direct evidence of rituals at Guadalperal during Roman times. Obermeier's 1920s excavations found a Roman coin and the remains of a small hut on the mound surrounding Guadalperal.
The dolmen and the Roman city are just fragments of the ancient landscape of Spain drowned beneath reservoirs built at the command of dictator Francisco Franco in the 1960s. At Guadalperal, the Valdecañas Dam blocked the Tagas River to create the Valdecañas Reservoir. "In this reservoir of Tagus, we have Roman cities and bridges, Iberian boars, medieval water mills, as well as abundant megalithic sites," explained Ramirez. "These underwater sites offer a unique image of the landscape in the 1960s, when agriculture in Spain had not been mechanized yet, and ancient sites were thoroughly preserved."
As a result of the dam building, the same thing happened all around the country, without regard for preserving — or even documenting — the archaeological sites being flooded. “This interest in Guadalperal dolmen allows us to put on the table a little known problem even in Spain: the need to establish an inventory of underwater sites, and a comprehensive documentation of these sites and their heritage values, with a compensation to the areas where this has happened, ”Ramirez told Ars.
This year's drought conditions may make surveying a little easier in some places, but it also means sites like the Guadalperal dolmen stand exposed to tourists whose foot traffic and exploration could damage the site. And Guadalperal is just one good rainstorm away from vanishing the water again for several more years — and it may emerge in worse shape.
The flooding has been kind to porous granite, many of which show signs of erosion, and a few of which are beginning to crack. Some stones that stood upright in the 1920s have since fallen over. Because of those concerns, a heritage preservation organization in Spain called Raices de Paraleda has advocated relocating the monument to a higher ground.
But relocation efforts would be costly, and they risk erasing important information about the context of artifacts and structures that can tell archaeologists how ancient people built and used the site. "Before making any decision, it is essential to have information about the archaeological context and the territory surrounding the monument," Ramirez told Ars. "It is also important to consider all the legal issues that affect this case."
Even if moving the dolmen itself proves feasible, that still leaves other sites, like the Roman city of Augostóbriga, all washed up.