Bryn Celli Ddu pillar identified as blue schist, not dressed stone

Bryn Celli Ddu pillar identified as blue schist, not dressed stone. Bryn Celli Ddu is a passage grave containing a burial chamber with a freestanding stone pillar Literature described the pillar as a carefully dressed, shaped stone that was not structural to the roof On the filming visit, the presenters concluded the pillar resembled a fossil tree trunk rather than cut stone

The burial chamber pillar at Bryn Celli Ddu, long described as dressed stone, is actually blue schist! Cardiff archaeologist Fion Reynolds and a geologist identified this rare metamorphic rock — it only forms in tectonic subduction zones, giving it a natural wood-grain texture. The Neolithic builders likely saw it as a magical stone-tree, deliberately placing it in the chamber. Those "axe-cut" notches? Probably natural features all along. What a brilliant recontextualisation of the site's purpose! 🪨🌿

Key Facts

• Bryn Celli Ddu is a passage grave containing a burial chamber with a freestanding stone pillar
• Literature described the pillar as a carefully dressed, shaped stone that was not structural to the roof
• On the filming visit, the presenters concluded the pillar resembled a fossil tree trunk rather than cut stone
• The pillar displayed notches that appeared to be axe-cut marks
• Cardiff University archaeologist Fion Reynolds and a geologist later identified the pillar as blue schist, a rare metamorphic rock
• Blue schist forms only in tectonic plate subduction zones, giving it a rolled, wood-grain-like appearance
• The prehistoric builders likely perceived the rock as a magical stone-tree, which recontextualises its purpose in the burial chamber

Source: NINE TIMES that Filming Archaeological Sites Completely Changed the Story by The Prehistory Guys