This summer, as Spanish locals sweltered through a severe drought, archaeologists were dealt an intriguing consolation prize: the re-emergence of the Dolmen of Guadalperal.
Dubbed by some the ‘Spanish Stonehenge’ and previously submerged beneath a reservoir, this 7,000-year-old megalithic monument, in the western region of Extremadura, consists of around 100 stones, some six feet tall, arranged in an oval formation. It would have served as a ceremonial tomb.
In something of a historical puppet show, the site, first excavated in the 1920s, was flooded in 1963 when the Valdecañas Dam was built; rendering its tips only visible when water levels dropped.
A 1990s drought once revealed the top half, but this is the first time it has been stripped of all water and exposed in its entirety.
The Dolmen of Guadalperal is estimated to have been erected in the 5th millennium BC – a chapter in human history during which the wheel was invented and agriculture was spreading through parts of Europe – and would have been enclosed by a roof.
Angel Castaño, a local historian, told Atlas Obscura: “Like Stonehenge, [the megaliths] formed a sun temple and burial ground. They seemed to have a religious but also economic purpose, being at one of the few points of the river where it was possible to cross, so it was a sort of trading hub.”
One of the larger stones, which would have formed the tomb’s entrance, is inscribed with symbols – among them a human figure and what is believed to be a snake.
The site was first excavated between 1925 and 1927 by German archaeologist Hugo Obermaier, whose findings weren’t published until 1960. A mere three years later, it was swallowed by the newly built reservoir.
Time may have preserved this impressive feat of construction, but the water has not been kind to it. Granite is highly porous and vulnerable to erosion, causing some of the megaliths to crack or fall over.
Primitiva Bueno Ramirez, a prehistory specialist at the University of Alcalá, remarks: “You couldn’t believe how many authentic archaeological and historic gems are submerged under Spain’s man-made lakes.”
What to do with the ruins next, before water consumes them again, is uncertain, but those who wish to study it have called for the megaliths to be moved somewhere high and dry. One petition has garnered more than 40,000 signatures.
In the meantime, since news broke of the Dolmen’s reappearance, tourists have reportedly started trickling in, and as can been seen in a photo published by local news outlet Hoy, there appears to be no measures in place to stop them touching, and potentially damaging, the rocks.
Concerning though this may be, a renewed interest in this otherwise forgotten archaeological site could be its only lifeline.
Other sites uncovered by extreme weather
Kemune Palace, Iraq
In June, a drought that drained a reservoir on the banks of the Tigris river in Iran pulled back the curtain on a 3,400-year-old Bronze Age palace. The Mosul Dam in Kurdistan was built in the 1980s, drowning the area and concealing the remains of the site.
A German-Kurdish alliance of archaeologists who quickly set about excavations declared it an “archaeological sensation”. It would have been built at the height of the Mitanni Empire, a slice of history about which little is known, and the investigation of its ruins is hoped to bring with it more clues. Murals and tablets are so far among the discoveries.
The ancient Kemune Palace was first discovered in 2010 but until now the water levels have not sunk low enough for excavations. Scripture recovered from some of the tablets, written in cuneiform, has been sent to Germany for study.
Wat Nong Bua Yai, Thailand
This summer saw Thailand experience one of the worst heatwaves in a decade, and thus the re-emergence of a once forgotten Buddist temple, Wat Nong Bua Yai, in the ancient region of Lopburi.
The temple itself is not particularly old but has been underwater, again the result of a dam flooding it, for 20 years. When the water in the reservoir dropped to less than three per cent of its capacity, so appeared remnants of Wat Nong Bua Yai, complete with a 13-feet tall Buddha statue, minus a head.
Local resident Yotin Lopnikorn told Reuters: “When I was young, I always came to meet friends at the elephant sculptures in front of the main building to play there.” Having seen it again in adulthood, he is keen for the temple to be “saved”. Thousands of tourists flocked to see it after word got around of its comeback.
The drowned English village
In July 2018, parts of a historic estate in Dartmoor, 15th-century Longstone Manor, were visible due a heatwave that drained the Burrator Reservoir to unprecedented levels.
The region was first flooded in 1898, losing a number of landmarks in the process, then again when the reservoir was expanded in 1929, claiming more of Longstone Manor.
Professor Bob Stone of the University of Birmingham told the BBC: “Many people talk about this drowned village at Burrator that only appears when there is a severe drought. There's a popular myth that when the water is low enough the spire of the village church will appear above the waterline and the bells will chime.”
What does exist, “many feet down”, Stone says, is the remains of an old farmhouse and Sheepstor Bridge.
Elsewhere in the UK
In 2014, a fierce storm stripped sand and water from the shores of Cornwall and Wales to uncover previously submerged forests (or rather, the remaining tree stumps) that date back to prehistoric times.
While scientists have long known of the existence of these forests, geologists were finally able to use radioactive carbon dating on the Mount Bay specimens and discern that forests extended across the entire bay between 4,000 to 6,000 years ago. This is a time period when human communities in Britain were slowly abandoning hunter-gatherer lifestyles for farming.
It’s not just the retreat of water that reveals secrets from the past. Thanks to Britain’s heatwave last summer, the discovery of two prehistoric villages were among 1,500 lost landmarks to have been uncovered; neolithic treasures resembling crop circles that are usually hidden beneath vegetation.
Archaeologists say they occur because the heat causes grass or crops grow differently on top of old sites, resulting in ancient walls and enclaves to emerge like ghostly blueprints.
The recent findings date from between the Stone Age, some 5,000 years ago, up to 16th-century Elizabethan England. Sites of particular interest included two Bronze or Iron Age settlements from Lansallos in Cornwall and Stoke by Clare in Suffolk, in which the outlines of roundhouses, animal enclosures and burial mounds can be seen.
In Scotland, Iron Age burials, Neolithic pits and prehistoric settlements have also been located in the same way, in this case from aerial surveys conducted by Historic Environment Scotland.
A similar climate phenomenon occurred in 2014 at Stonehenge, when surrounding grass dried out to reveal the faint outline of missing megaliths, proving the long-contested theory that the stones once formed a full circle.
Inspiration for your inbox
Sign up to Telegraph Travel's new weekly newsletter for the latest features, advice, competitions, exclusive deals and comment.