What if someone were to drill a hole in one of Stonehenge’s mighty piers today? And not in a hidden place and not with the small drill, but across a block? This is exactly what happened during restoration work in 1958 to coax a few final secrets from the famous place of worship. The workers took a drill core at three points from stone 58, a fallen pillar from the inner ring of the 4,500-year-old facility. The stone rods, each about one meter long, were not examined at the time, however, it was not the time for sophisticated microscopic high-tech analyzes. No archaeologist took care of the drill cores. Soon no one knew where the scientifically so valuable rods had actually ended up.
Now two of the three lost stone sticks have been reappeared and analyzed. The extensive research enabled experts led by David Nash from the University of Brighton to take a look deep inside a pillar of the monument for the first time. report the archaeologists in the specialist magazine Plos One. It is the most comprehensive study to date of original rock from the thick blocks of the facility in the south of England. It is important to determine the chemical composition of the 52 sandstone blocks that are still preserved and weigh tonnes, for example to locate the quarry in which they were mined and thus to decipher the history of the megalithic structure.
The drill core hung on an office wall as jewelry
The story behind this investigation begins three years ago when a 90-year-old Florida man reported to the British authorities. According to Robert Phillips, it had a drill core from one of the large blocks of sandstone from Stonehenge, the so-called sarsen stones. He would like to return this to Great Britain before his death. Phillips, a former restorer at the Van Moppes drilling company, which was involved in the restoration work at Stonehenge, was allowed to keep the cylindrical drill core as a souvenir. Together with a watercolor of the work that his company had made, he hung the drill core in a Plexiglas tube above his desk in his office in Basingstoke, England. When he retired in 1976, he was allowed to keep the core and the image. In 1977 he emigrated to the USA, where he moved several times, and kept the stone staff until the end.
The pier 58 drilled by him belonged to a so-called trilith, a group of three consisting of two bearing stones and a transverse capstone. It is precisely these towering gateways that are the hallmark of the monumental complex. They once formed a covered ring, which contains other constructions inside, including smaller ones arranged in a circle, so-called bluestones and five triliths because of their color. One of these groups of three overturned on January 3, 1797 after a sudden thaw. Historical reports suggested underground rabbit burrows as the cause of the instability.
In order to make it easier for visitors to understand what the circular system once looked like, the distinctive group was to be restored to its original state. One of the pillars also had incisions, which were endangered because visitors always climbed the stones. So in June 1958 the restorers put the stones back together with the help of a crane truck. They discovered a dangerous crack at stone 58. In the historical files that are now in the National Archives in London, they noted with concern: “We found that the well-known longitudinal fracture of stone 58, one of the pillars of the Trilith, turned out to be more extensive than expected when it was erected. and we backed the Ministry’s proposal to strengthen the stone. ” And so on August 20, 1958, Phillips took three drill cores out of the stone, sunk metal anchors and dowels and later closed the holes with original stones from the system.
The 108 centimeter long core that has now emerged has broken into six parts, the fragments are between 6.7 and 29 centimeters long. The first evaluations of samples had already led to spectacular findings last year. Most of the total of 52 large stone giants of the Stonehenge monument therefore very likely come from West Woods, an approximately six square kilometers large, now largely forested plateau about 25 kilometers north of Stonehenge.
Bluish kyanite and cognac colored zircon
Now the detailed analysis of the fragments followed. To do this, the experts working with David Nash and the archaeologist Mike Parker Pearson sawed up the smallest, 6.7 centimeter long fragment. And then checked the surfaces with all currently available technologies. “We scanned the rock with the CT, irradiated it with X-rays, viewed it under different microscopes and analyzed its sedimentology and chemistry,” says Nash. With the exception of thin section analyzes and some chemical methods, all of the techniques the archaeologists used in their study were new to Stonehenge, says Nash.
The results are quite astonishing: Stone 58 consists of 99.7 percent of a type of cement made of fine and medium-sized quartz sand grains, and the researchers also found traces of titanium oxide, iron oxide, magenta-colored tourmaline, bluish kyanite or cognac-colored zirconium. The photos clearly show that the quartz grains formed an “interlocking mosaic of crystals,” says Nash. That made the rock more durable, it was a kind of quartz cement. The researchers were surprised by the hardness and durability of the sarsen. All pillars were made of the same hard stone, but softer sandstone was used for the foundations.
These material properties were certainly good reasons for the builders to transport this type of rock 25 kilometers over undulating terrain to Stonehenge. After all, the sarsen stones weighed up to 25 tons. Nash certainly suspects technical material knowledge behind the selection, because the quartz cement is well hardened and therefore incredibly strong. After all, closer quarries could have been used for the construction.
Some grains of sand are 1.6 billion years old
Nash and his team also determined the original age of the sediments in the sarsen. These were already deposited in the so-called paleogene, a geological time between 23 and 66 million years ago. They even dated the neodymium isotopes contained in quartz rock to the time of the dinosaurs, to the Mesozoic era 66 to 252 million years ago. Some grains of sand are even older, up to 1.6 billion years old. From that point of view, Stonehenge is really ancient, at least in tiny parts.
After intensive research, the archaeologists discovered at least a fragment of the other two drill cores made of stone 58, which were taken in 1958. It had been forgotten in a box in the Salisbury Museum in England, although it had clearly said: “3 times Stonehenge stones from the treasure chest”. Why no one had looked at these precious pieces for decades remains one of Stonehenge’s many mysteries.