“Their analysis matched the stone’s profile with old red sandstone deposits from northeast Scotland”
New evidence that the Chicxulub impactor came from beyond Jupiter may settle an old debate in cosmo-chemistry
Cue the conspiracy theories: new research reveals that one of Stonehenge’s central and larger megaliths came neither from England, nor Wales, but from the far northeast of Scotland – and we don’t know how it got there. Experts think the six-tonne altar stone must have been dragged or floated at least 750km (466 miles) south to complete the prehistoric monument.
Published in the journal Nature, the new findings contradict existing beliefs that the altar stone came from Wales.
Dr Robert Ixer, honorary senior research fellow at University College London (UCL) and one of the study authors, told BBC Science Focus the discovery was “a great surprise. My first thought was disbelief.”
He added: “It has an enormous significance. This Wessex-Orkney Isles connection has been known for decades, but its significance has been disputed, hotly and acrimoniously.” The altar stone is a 50cm-thick (20in) sandstone block in the middle of Stonehenge’s circle. It’s believed that, along with the rest of the structure, the stone appeared in its current location near Salisbury about 5,000 years ago.
Previous analysis of the site identified two main types of stone used in the construction. These are sarsens, the iconic outer stones sourced from near Marlborough, about 25km (15.5 miles) away, and the inner bluestones, of Welsh origin from Pembrokeshire’s Preseli Hills.
The largest of these bluestones, the altar stone, is barely visible to visitors, lying flat on the ground and mostly covered by two large, fallen sarsen stones. The research team studied the age and chemistry of mineral grains retrieved from fragments of the altar stone. Their analysis matched the stone’s profile with old red sandstone deposits from northeast Scotland – while also highlighting key differences with Welsh bedrock.
“Our analysis found specific mineral grains in the altar stone are mostly between one to two billion years old, while other minerals are around 450 million years old,” said lead author Anthony Clarke, PhD student at Curtin University, Perth, Australia. “This provides a distinct chemical fingerprint, suggesting the stone came from rocks in the Orcadian Basin in Scotland.”
Moving the stone from Scotland would have been significantly harder than from Wales. Geographical features and forests throughout Britain at the time would also have made the process difficult, suggesting use of unexpectedly advanced transport methods and societal organisation at the time of the stone’s arrival in England.
“Transporting such massive cargo overland from Scotland to southern England would have been extremely challenging, indicating a likely marine shipping route along the coast of Britain,” said Christopher Kirkland, a professor at Curtin University and a co-author of the study. “This implies longdistance trade networks and a higher level of societal organisation than is widely understood to have existed during the Neolithic period in Britain.”
While the team has celebrated establishing the age and chemical ‘fingerprint’ of the Scottish stone, mysteries still remain – including its precise, original location. Current candidates include Orkney, a patch of land in Caithness or a narrow coastal strip stretching from Inverness to Elgin.
New evidence suggests that the asteroid behind the mass extinction event that killed the dinosaurs didn’t come from nearby, but from very far away: the outer parts of the Solar System, beyond Jupiter. The authors of the research, published in the journal Science, say their research finally settles a longstanding debate about this crucial chapter in Earth’s history.
“This is one of those studies that makes you stop in your tracks and think about the cosmic
interconnectedness of everything,” palaeontologist Prof Stephen Brusatte of University of Edinburgh, who wasn’t involved in the study, told BBC Science Focus. “To think that this bit of space junk, from such a far off and remote place, somehow, someway, against the odds intersected with Earth and the dinosaurs… It’s such an unlikely story, but it actually happened.”
This moment in time, between the Cretaceous and Paleogene, is captured in the layers of rock buried under Earth’s surface across the world. In geology, this layer of rock is known as the Cretaceous–Paleogene boundary, or K-Pg boundary. Here, scientists have previously found high levels of platinum-group elements (including iridium, ruthenium, osmium, rhodium, platinum and palladium).
These elements are rare on Earth, but common in meteorites. Nevertheless, some scientists have previously thought that the high levels of these elements could have been caused by widespread volcanic activity. Others thought, however, that the specific composition of elements, known as the isotopic signature, aligned more with that of asteroids.
To settle the debate, the researchers took samples from the K-Pg boundary. Comparing the chemical signature against samples from other asteroid impacts, they discovered that the levels of ruthenium isotopes were not similar to those found on Earth or in other meteorite types. Instead, they closely matched extraterrestrial carbonaceous chondrites: a rare type of asteroid that formed beyond Jupiter in the early Solar System.
“To think that this bit of space junk, from such a far off and remote place, intersected with Earth…”