Altar stone origin traced to Scotland, once stood upright. Altar stone provenance recently determined to be from the Orcadian basin in northeast Scotland Previously thought to come from Preseli Hills in southwest Wales. or Brecon Beacons Orcadian basin contains the oldest rocks in Britain, north of the Iapetus Suture
Stonehenge's altar stone came from northeast Scotland—not Wales as previously thought. Analysis of sandstone fragments revealed this. A 1950s excavation uncovered a stone hole containing a fragment of a Group 1 stone axe. Researchers are uncertain whether the altar stone originally stood upright. Its current orientation captures solar and lunar alignments.
Key Facts
- Altar stone provenance recently determined to be from the Orcadian basin in northeast Scotland
- Previously thought to come from Preseli Hills in southwest Wales. or Brecon Beacons
- Orcadian basin contains the oldest rocks in Britain, north of the Iapetus Suture
- Discovery made by analyzing blue stone fragments broken off the altar stone in 19th-century excavations
- Richard Atkinson found a stone hole in the 1950s containing a fragment of a Group 1 stone axe
- Theory: altar stone originally stood upright on the primary axis at stone hole WA 3639
- When the big stone phase was built around 2500 BC, the upright was removed and laid flat
- The 80° angle of the altar stone relative to the primary axis captures all solar and lunar alignments
- Five stones (four station stones plus upright altar) could capture the entire sky at Stonehenge's latitude
- Stone 11 was added later to preserve the sight line from the original upright position
- Theory suggests people from Orkney understood the sky geometry and traveled south to find the right latitude
- This may explain why the monument was built where it is, centered on the altar stone's position
Related site: Stonehenge — view location, images, and history on the Ancient Nerds map.
Source: The Astronomy of Stonehenge | Simon Banton | Origins Conference by MegalithomaniaUK