Spanish drought reveals submerged megalithic tomb

A drought in Spain revealed an ancient circle of stones concealed 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 the construction of a dam in the 1960s.

The Guadalperal dolmen

The rocky exposed soil of the reservoir is today punctuated by about 150 granite stones formed from concentric oval rings around a chamber about 5 m wide, intended to be introduced by a passage lined with megaliths facing east. It has earned the nickname "Spanish Stonehenge", but it is a false name. Unlike Stonehenge, Guadalperal was not an open monument.

The standing menhirs today form the backbone of a funeral mound. Once, the spaces between the concentric rings would have been filled with earth and pebbles, and the vertical stones would have supported a roof of horizontal slabs. A mound of earth would have covered the whole; you can still see the remains of this structure in the sand and gravel bank that now surround the standing stones.

At the inner end of the passageway, marking the entrance to the master bedroom, a stone, or menhir, carries the carved image of a snake and several cups. Primitiva Bueno Ramirez, archaeologist at the University of Alcalá, describes the stone as "engraved showing a human body, shoulders attached and a cut head. From one side of the body, [there is] a sinuous line with a triangular head, which could be described as a snake. "Very similar images were found engraved or painted at the entrances of another dolmen in Spain, and the direction of the passage means that the morning sun would help illuminate the image.

Archaeologists have documented more than 400 similar monuments in Spain, mainly along the Tagus and Douro routes. They are usually associated with the remains of the first agricultural colonies in Spain, and burials in dolmens often include artifacts from Bell Beaker's culture. The crop first appeared in Spain around 4,750 years ago and has spread to central and western Europe and northwestern Africa around 4,500 years ago.

A missing body

No human remains have been returned to Guadalperal. When archaeologist Hugo Obermaier excavated the site in the 1920s, he found polished tools, flint and pottery – the typical set of objects for a megalithic site, many of which were features of Bell Beaker's culture – but no people.

"But we have data on the excavations carried out in the megaliths near the Guadalperal, like Azután, in Toledo, whose architecture is almost identical, where human remains have been detected," Ramirez told Ars. Archaeologists have X-rayed the remains of people buried in the dolmen in Azután, and because the construction of Azután is almost identical to that of Guadalperal, Ramirez suggests that they are the same age: between 5,000 and 6,000 years .

But the stones themselves may have been extracted much earlier. Ancient people have often moved the menhirs from the oldest graves, often with the graves themselves, with the occupants buried in the new dolmen. "There is evidence that older menhirs have been used as initial components of many dolmens," Ramirez and his colleagues wrote in a 2015 book, The megalithic architecture of Europe.

The Spanish past drowned

A nearby Roman city, the city of Augostóbriga, is also submerged by the reservoir. It is likely that the local population still used the monument while the Romans occupied the area. "Other Iberian and European megalithic memorials show the uses or rituals of dolmens in Roman times," Ramirez told Ars, adding that there was no direct evidence of rituals in Guadalperal at the time. Roman era. Obermeier's excavations in the 1920s uncovered 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 under tanks built under dictator Francisco Franco in the 1960s. In Guadalperal, the dam of Valdecañas blocked the Tagas River for create the reservoir of Valdecañas. "In this reservoir of the Tagus we have Roman cities and bridges, Iberian wild boars, medieval watermills, and many megalithic sites," said Ramirez. "These underwater sites offer a unique picture of the landscape in the 1960s, while agriculture in Spain was not yet mechanized and that ancient sites were perfectly preserved."

As a result of the construction of the dam, the same thing has happened across the country, whether to preserve, or even document, archaeological sites during flooding. "This interest in the 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 complete documentation of these sites and their heritage values, with compensation for the areas where this occurred, "said Ramirez to Ars.

This year's drought may make this type of survey a little easier in some places, but it also means that sites like the Guadalperal dolmen are exposed to tourism, whose pedestrian traffic and exploration could damage the site. And Guadalperal is no more than a good storm of rain that can disappear under water for several more years – and it is likely to deteriorate even worse.

The flood did not affect the porous granite of the menhir, many of which show signs of erosion and some begin to crack. Some stones that stood in the 1920s have since fallen. Due to these concerns, a Spanish heritage protection organization, Raices de Paraleda, has advocated for the relocation of the monument in height.

However, relocation efforts would be expensive and could erase important information about the context of artifacts and structures, which could indicate to archaeologists how ancient populations built and used the site. "Before making a decision, it is essential to have data on the archaeological context and the territory around 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 is feasible, it still leaves other sites, such as the Roman city of Augostóbriga, all stranded.