考古学：ストーンヘンジの祭壇石はスコットランドを起源としているかもしれない

The Altar Stone at Stonehenge may have been sourced from northeast Scotland, an analysis published in Nature suggests. The findings provide further insights into the culture and connectivity of prehistoric Britain and suggest a high level of societal organisation.

Previous analysis of the Neolithic site of Stonehenge, in the southwest of England, has identified two main types of stone used in the construction of the stone circle: sarsens, sourced from the West Woods near Marlborough (around 25 km away), and the bluestones, some of which have been shown to have a Welsh origin. The Altar Stone is the largest of the bluestone megaliths and its origins are unknown, with previous research discounting an Anglo-Welsh origin.

Anthony Clarke and colleagues analysed the age and chemistry of zircon, apatite and rutile grains from two fragments of the Altar Stone. The zircon within the fragments was largely from Mesoproterozoic (around 1,600–1,000 million years ago) and Archaean sources (approximately 4–2.5 billion years ago), whereas apatite and rutile were comprised largely from a mid-Ordovician source (between 470 million and 458 million years ago). Further age comparisons to sedimentary deposits in Britain and Ireland revealed a striking similarity to the Old Red Sandstone of the Orcadian Basin in northeast Scotland, which the authors suggest could be the origin of the Altar Stone. This implies that the Altar Stone was sourced around 750 km from its final placement. The authors note that land transportation would have been difficult owing to geographical features and the forested nature of Britain at the time. They propose that the stone may have been transported via a sea route from northeastern Scotland to southern Britain.

These findings suggest a high level of societal organisation within Neolithic Britain that enabled long-distance transportation, the authors conclude.