The Mystery of Stonehenge's Altar Stone

The altar stone at Stonehenge was a big mystery. Scientists found its origin in 2024. The rock came from north-east Scotland. It was a 5-meter-long sandstone. It weighed 6 tonnes. A glacier could have carried it south. But the glacier idea was unlikely. Researchers think humans moved the rock. The rock's chemical fingerprint matched rocks in Scotland. Anthony Clarke was a researcher from Australia. He said each grain of sand had an age and composition. The team compared the rock to others in the UK. They found the origin was the Orcadian basin in Scotland. The rock traveled 750 kilometers. A glacier could have moved the rock. Ice flow modelling showed some ice went south. It would have left the rock at Dogger Bank. Dogger Bank was a land bridge then. It flooded 8000 years ago. Stonehenge was built 5000 years ago. So the rock would have waited 3000 years underwater. That was unlikely. Humans moved other big stones at Stonehenge. Those stones weighed 25 to 30 tonnes. They moved them tens of kilometers. So humans had the tools and will. They were not in a hurry. The project could be multi-year. Clarke said it was like building pyramids. The researchers will take more samples. They hope to find the exact quarry. But we will never know why people did this. Clarke compared it to choosing marble for a kitchen. People always liked special rocks.