Altar stone origin traced to Scotland, once stood upright

March 02, 2026

EnglandArchaeoastronomy

Megalithic structures4500 - 3000 BC

Source: The Astronomy of Stonehenge | Simon Banton | Origins Conference by MegalithomaniaUK

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