One of the most enduring mysteries surrounding the colossal Stonehenge monument—the origin of its largest stones—has finally been solved. Through pioneering geochemical analysis, scientists have confirmed that the majority of the huge sarsen stones that form the iconic outer circle and central horseshoe came from West Woods, a nearby forest only about 25 kilometers (15 miles) north of the site. This groundbreaking discovery, made possible by a piece of stone core returned after six decades, provides unprecedented insight into the logistical and engineering efforts of the Neolithic builders around 2500 B.C., shifting the focus from “where” to “how” they moved these 20-tonne megaliths across the landscape.
The Chemical Fingerprint That Revealed the Source
For centuries, the origin of the 52 surviving sarsen stones at Stonehenge remained speculative. While the source of the smaller bluestones had been famously traced to the Preseli Hills in Wales nearly 200 miles away, the larger, chemically more homogeneous sarsens proved elusive. Experts generally assumed they came from the Marlborough Downs, but lacked the definitive proof to pinpoint the exact location.
The breakthrough came from an unusual source: a core sample drilled from Stone 58 during restoration work in 1958. After being kept as a souvenir in the US for 60 years, it was returned to English Heritage in 2018. This provided researchers with a rare opportunity to perform a destructive analysis on a part of the ancient monument. They first used a portable X-ray fluorescence spectrometer (pXRF) to non-destructively analyze all the standing sarsens, confirming that 50 of the 52 stones shared a consistent chemical signature.
Pinpointing West Woods: A Practical Choice
With the consistent chemical fingerprint established, the team compared it against samples of sarsen stone collected from 20 different potential source areas across Southern Britain. The analysis of the returned core, using more advanced mass spectrometry, provided the definitive match. It showed that the composition of the Stone 58 core was chemically identical to sarsens found in West Woods, an area on the edge of the Marlborough Downs.
This finding suggests that the Neolithic builders had a clear, coordinated plan. Rather than collecting stones from various scattered locations, they sourced almost all the giant sarsens from a single, relatively close area. Historians now propose that the overwhelming factor in choosing West Woods was the size and availability of the largest, most substantial stones, prioritizing logistical practicality over symbolic distance for the monument’s main architectural elements.
Understanding the Herculean Effort
The confirmed, relatively short travel distance of 25 kilometers (15 miles) now allows archaeologists to shift their focus to the Herculean logistical challenge of the move itself. Transporting a 20-tonne stone without the aid of wheeled vehicles or domesticated horses across the undulating terrain of Salisbury Plain would have required tremendous planning, organization, and manpower.
Researchers are now actively modeling the most probable transport routes that the builders would have taken. Did they use sleds over wet ground? Or did they follow the River Avon for part of the journey? The finding of a single source also highlights the unity and sophisticated social coordination required by the communities who collaborated to extract, shape, and erect these monumental stones, a construction effort that lasted for centuries.
Remaining Mysteries of the Stone Circle
While the sarsen mystery is resolved, the composite nature of Stonehenge continues to deepen its enigma. The origin of the two non-matching sarsen stones remains unknown. Furthermore, the incredible revelation that the Altar Stone, a large slab at the heart of the inner structure, may have been brought from as far away as Northeast Scotland (a distance of over 700 km) suggests two very different approaches to stone selection.
It appears the builders valued local practicality for the vast, structural Sarsen stones but undertook extraordinary long-distance efforts for certain special stones, like the bluestones from Wales and the Altar Stone from Scotland, likely due to their perceived symbolic, ancestral, or ritual significance. This layering of efforts reveals a complex and geographically connected prehistoric British society.
