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It is a rock of the ages.
A long-lost piece of Stonehenge has revealed that the prehistoric monument was nearly 2 billion years old, giving new insight into its ultra-durable composition, according to a new study.
Robert Phillips, a monument restorer in England in 1958, brought home a fragment of rock that was recently unearthed and studied by researchers at the University of Brighton in England.
The fact that the monument’s minerals formed 1.6 million years ago – around the time when dinosaurs roamed the Earth – explains why it took so long, the university’s geomorphologist told Reuters from Brighton, David Nash, who led the study.
“This explains the resistance of stone to weathering and why it is an ideal material for building monuments,” Nash said.
The study showed that the rock’s silcrete compound is largely composed of grains cemented tightly together by interlocking quartz crystals, which is extremely durable and does not crumble or erode easily even when ‘he’s exposed to the elements.
Megaliths are made of a stone called silcrete, which gradually formed a few meters from the surface as a result of the washing of groundwater through the underground sediments.
Researchers studied a core of the rock, called Stone 58, which was kept in the United States for decades before being sent back to Britain for research in 2018. The sarsens were erected at the site of the Salisbury Plain in Wiltshire by Late Neolithic men circa 2500 BC. .
On Wednesday, researchers described the in-depth study, which provided insight into one of the 52 sandstone megaliths at Stonehenge, known as the sarsens, providing insight into its geology and chemistry, according to Reuters.
Stone 58 is approximately 23 feet tall, with 7 feet below ground and an estimated above ground weight of 24 tons.
The carrot sample – about an inch in diameter and about a yard long – is brighter than the pale gray exterior of the megaliths.
It was given as a memento to Robert Phillips, who worked for a company involved in conservation work. He took it with him with his permission when he emigrated to the United States in 1977. In 2018 he decided to send it back to the United Kingdom for research. He passed away in 2020.
“Accessing the core drilled from Stone 58 was really the holy grail of our research,” Nash told Reuters. “All previous work on the sarsens at Stonehenge involved samples either excavated at the site or extracted from random stones.”
Scientists used CT scans, x-rays, microscopic scans, and other techniques to study fragments of the core.
“This small sample is now probably the most analyzed piece of stone other than moon rock,” Nash said.
“The sandy sediments in which the stone developed were deposited during the Paleogene period, 66 [million] at 23 million years old, so sarsens can’t be older than that, ”Nash told Live Science.
But when the researchers compared the ratios of neodymium isotopes – or atoms of the element with different numbers of neutrons in the nucleus – in the samples, they found that some sediment was even older, according to the journal. .
Some grains were probably eroded from rocks dating from the Mesozoic era, while they may have been pounded by dinosaurs, according to Nash, who said some of the grains formed 1 billion to 1.6 billion years ago during the Mesoproterozoic era. .
The results were published in the peer-reviewed journal PLOS ONE.
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