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Each of the 32 colossal stones in the Menga Dolmen, a 5,600-year-old megalithic monument in southern Spain, is much larger than the largest megaliths at Stonehenge, the most famous Neolithic wonder.
Embedded in the ground on top of a hill that rises about 50 meters (165 feet) above the surrounding plain, the stones form a dolmen, or one-chamber tomb, about 25 meters (82 feet) long and 5 meters (16.4 feet) wide. at the widest point. The largest single stone weighs about 150 metric tons, about the same as a blue whale and almost five times heavier than the largest component of Stonehenge. Together, the megaliths weigh about 1,140 metric tons.
“I tell the students in my lectures … the weight is more than two Boeing 747 airplanes together, the ones that fly across continents and so on, fully loaded with fuel and passengers,” said Leonardo García Sanjuán , co-author of a new study on the monument and professor of prehistory at the University of Seville in Spain.
“It’s a huge, huge stone, and it’s always been a mystery and an interesting scientific question how on earth (it was built) with the technology they had in the Neolithic period.”
The results of a decade-long research project published Friday in the journal Science Advances attempt to answer this question, demonstrating the sophisticated engineering skills required to accomplish such a feat.
“I noticed that his stones were carefully placed without gaps but this paper shows how precisely that needs to be done, with an extraordinary eye for the dimensions and angles,” said Mike Parker-Pearson, professor of prehistory the British later. at University College London, who described it as “one of the greatest megalithic wonders of the world”. Parker-Pearson was not involved in the research.
How to build a megalith
The project, led by José Antonio Lozano Rodríguez, a geologist at the Canary Islands Oceanographic Center, pieced together how the stones were cut, transported and placed by looking at the topography and geology of the site, information from previous archaeological excavations, and ethnography and historical accounts of construction techniques.
The straight stones in the walls of the room were not vertical, leaning in at a gentle angle to make the building narrower at the roof than at the floor and creating a trapezoid-shaped room.
The team calculated that each of the stones would continue to stand in at a largely uniform angle of 84 to 85 degrees. The stones continued to stand on the walls side by side together at a consistent angle. The architect and builders must use tools such as plumb levels and framing squares to achieve such consistency and accuracy, the study said.
“The precision of the angles is millimetric,” said García Sanjuán. “They made Tetris out of this, like the computer game.”
He added, “The stones were placed and carved so that they were slightly inclined and fitted together perfectly. Each block must fit directly into the others, and each block supports the others. All the stones are locked into each other and embedded into the bedrock.”
A distinctive feature of the monument revealed by the study was how the stones were originally embedded upright, probably using a counterweight, into the sockets of the foundations so deep that up to a third of the stones were underground when placed up them for the first time.
When the walls were finished, the builders placed five huge capstones to form the roof. The builders then removed the earth to the required floor level, erecting stone pillars for additional support.
“When the capstones were added, it was like a solid box, with the bedrock still inside, and then they carved all that rock, all that bedrock, to make the room,” said García Sanjuán.
The resulting building was then covered with a mound of soil, which would have insulated the room from cold and wet weather, as well as acting as a “straitjacket” to add stability to the construction, he said.
García Sanjuán said that it is not clear exactly how the dolmen was used, probably as a temple and tomb, although few archaeological remains were found inside the ruin. The paper suggested that one reason it was built to withstand the ages is that the region is seismically active.
Parker-Pearson said its makers wanted to create a solid structure that would last forever.
“Although the authors of the Menga paper suggest that this may be something to counteract earthquake damage, I think there is a more significant reason why stone monuments such as Menga, Stonehenge and many others were built so that is firm, and that is the effort for permanence,” he added. said.
“I think this stone connection with the eternal is a feature shared by the prehistoric megalithic dolmens (and other tombs) in western Europe,” he said.
“In the majority of cases these are tombs and tombs for the dead, permanently housing the ancestors who were also considered eternal.”
How did they carry the rocks?
Research published by the same team in December 2023 identified the source of the stones used to build the monument: a quarry 850 meters (0.5 miles) away, about 50 meters (164 feet) higher than the Menga site — would be a favorable topography. the huge stones were allowed to be carried down a gentle slope.
This study indicated that the builders would probably have designed a path or road to minimize the friction of the relatively soft rock against the ground by embedding closely spaced wooden posts or planks in the ground and transporting the stones using wooden sledges huge controlled with big ropes.
The dolmen was also built on a similar descending path from the back of the room to the entrance, which allowed the stones to move along the same axis during the construction process.
“These new insights into the engineering skills, as well as the size of the dolmen’s colossal stones, confirm that these Early Copper Age Iberians intended to build a monumental monument,” Parker-Pearson said by email.
“With such large stones, they couldn’t afford to make mistakes when maneuvering them into place – if only one was a few centimeters out, it would be difficult to correction when a standing stone would have been laid in a construction trench.”
The new study described the Menga Dolmen as a one-of-a-kind example of “creative genius” and “early science” in Neolithic society, a time when agriculture was recently adopted as a way of life and tools were made by the most of it. stone and other natural materials other than metal, and there was no written language.
“You see these people knew about physics, friction, angles. They knew about geology. They knew the properties of the rocks, they knew about the geometry,” said García Sanjuán.
“Put these things together (and) what do you have? We have to call it science. We never talk about Neolithic science because we are too arrogant to think that these people could do science the way we do it.”
“If any engineer today tried to build Menga with the resources it had 6,000 years ago, I don’t think they could do it.”
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