Stonehenge had a tough Scottish coronary heart, a brand new examine suggests.
The traditional web site’s central stone, a big slab often known as the Altar Stone, consists of rock transported not less than 750 kilometers from northeastern Scotland to southern England, say geoscientist Anthony Clarke of Curtin College in Perth, Australia, and colleagues.
An evaluation of the age and chemical make-up of three kinds of mineral grains in two Altar Stone fragments recognized an in depth match to corresponding measures for a Scottish rock formation often known as the Orcadian Basin, the researchers report August 14 in Nature. Utilizing the identical measures, they dominated out different rock formations in the UK and Eire as sources for the Altar Stone.
The sandstone slab sits inside a semicircular arc of smaller stones, often known as bluestones. Many of the bluestones have been chemically traced to a rock supply in western Wales, round 225 kilometers west of Stonehenge. A greater than 5,000-year-old Welsh stone circle could have supplied preliminary constructing blocks for Stonehenge (SN: 2/11/21).
The brand new examine challenges a earlier assumption that the Altar Stone, attributable to its place close to the bluestone arc, additionally had Welsh roots.
A mix of estimated ages for the three minerals within the Altar Stone — which ranged from a number of hundred million to three billion years outdated — supplied a gauge for figuring out which present rock supply represented the most probably supply for the Stonehenge stone. Decay of small quantities of radioactive parts in crystallized minerals — such because the breakdown of uranium into lead in zircon crystals — happens at identified charges, which enabled Clarke’s group to calculate the age estimates.
Transferring a large stone to Stonehenge
Transporting the six-metric-ton Altar Stone from Scotland to southern England’s Salisbury Plain would have offered a frightening problem.
Altar Stone transport could have relied on the exact location it got here from, which has but to be established, geochemist Nick Pearce of Aberystwyth College in Wales stated at an August 13 information convention. The Orcadian Basin extends from northeastern Scotland to the Orkney Islands off Scotland’s northern coast. Transport by ship down England’s east coast earlier than lugging the Altar Stone about 160 kilometers to Stonehenge from the English Channel, relatively than a strictly overland route, makes extra sense if the Altar Stone got here from an island, Pearce stated.
Researchers have no idea when the Altar Stone arrived at Stonehenge. Development started round 5,000 years in the past (SN: 5/29/08). Initially serving as a cemetery, modifications and additions to the positioning occurred over the subsequent two millennia.
The sandstone slab could have been positioned among the many bluestones throughout a second building part between 2620 B.C. and 2150 B.C., the researchers suspect.
A Scottish supply for the Altar Stone provides to proof that more and more factors to long-distance connections, together with shared pottery types and home plans, amongst Late Neolithic teams that inhabited the British Isles throughout Stonehenge’s building phases, says archaeologist Alasdair Whittle of Cardiff College in Wales. Food plan-related chemical signatures in excavated bones have advised that some Late Neolithic home animals in southern England got here from the north, presumably Scotland, says Whittle, who didn’t take part within the new examine.
“This was an age of heroic feats of shared labor, motion and meeting, into which an Altar Stone from northeastern Scotland would completely properly slot in,” Whittle says.
The thriller of the Altar Stone’s orientation at Stonehenge
A Scottish origin for the Altar Stone additionally highlights an intriguing architectural hyperlink, says archaeologist Joshua Pollard of the College of Southampton in England. In contrast to different stones at Stonehenge, the Altar Stone lies on its facet — a element seen in some stone circles in Scotland.
Two collapsed stones from the monument’s outer circle relaxation atop the Altar Stone, which is damaged in two and has largely sunk into the grass. In distinction to the Altar Stone’s distant origins, these large outer-circle stones got here from a rock supply positioned 25 kilometers north of Stonehenge.
Researchers have no idea whether or not the Altar Stone initially stood upright.
A area of Scotland referred to as Aberdeenshire comprises as much as 99 recorded examples of Recumbent Stone Circles. In every case, a hoop of standing stones surrounds a slab laid on its facet within the ring’s southwestern or southern arc.
Aberdeenshire’s Recumbent Stone Circles symbolize “a really attention-grabbing architectural connection [to the Altar Stone],” says Pollard, who was not a part of Clarke’s group.
