Ancient society may have carved ‘sunstone’ to end volcanic winter

Hundreds of mysterious engraved “sunstones” unearthed in Denmark may have been ceremonially buried because a volcanic eruption around 2900 BC. made the sun disappear.

A total of 614 stone slabs and fragments of tablets engraved with decorative motifs of the sun or plants have been unearthed in recent years at the Vasagård West archaeological site on Bornholm. They were found in a layer dating to about 4900 years ago, when Neolithic people cultivated the area and built enclosures surrounded by earthen ramparts of banks and ditches.

Most of the carved sunstones were found in the ditches surrounding these enclosures and had been covered by a stone pavement containing fragments of pottery and other objects. The pottery is typical of the late Funnel Beaker culture, which was present in this region until about 2900 to 2800 BC.

It was originally suggested that the stone carvings of the sun were buried to ensure a good harvest. The sun was the focal point for the early agricultural cultures in Northern Europe, says Rune Iversen at the University of Copenhagen in Denmark.

“But why did they deposit all these images at the same time?” asks Iversen. “The last thing they basically did here was deposit these sunstones and then cover them with bits of animal bone, all the artifacts and that sort of thing. And we see that repeating itself from trench to trench. So it’s some kind of action or event. “

Now he and his colleagues have an answer. They looked at data from ice cores mined in Greenland and Antarctica and found higher concentrations of sulfate, which is deposited in the years after a volcanic eruption, in the period around 2900 BC.

The relative ratio of sulfate deposition in Greenland and Antarctica suggests the eruption was somewhere close to the equator, the researchers say, and its effects appear to have covered a huge area. Ash clouds may have blocked the sun and lowered the temperature for years.

A period of severe cooling around 2900 BC is confirmed by sources including tree rings in preserved wood from the Main River Valley in Germany and those from long-lived bristlecone pines in the western United States.

The eruption would have been devastating for the Neolithic peoples of Northern Europe. “If you don’t have the harvest and you don’t get the crops in, you won’t have anything to sow next year,” says Iversen. “They must have felt quite punished at the time because it’s just an endless disaster coming at them.”

He and his colleagues say the burial of the carvings could have been an attempt to bring back the sun or a celebration after the sky finally cleared.

“That’s a good explanation,” says Jens Winther Johannsen at the Roskilde Museum in Denmark. “You can be sure that hardy farming communities must rely on the sun.”

Lars Larsson at Lund University in Sweden asks why we only have evidence of such behavior on Bornholm, and not elsewhere in southern Scandinavia, if the climate effect was widespread.

This may be because people there had plenty of hard stone – slate – on which they carved the sun images, but much of the rest of southern Scandinavia is mostly clay, so there are less suitable stones to carve, says Iversen. “They could also have made engravings on pieces of wood or leather elsewhere,” he says, but these generally would not have been preserved.

Alternatively, it may reflect cultural differences, says Johannsen. “These communities are not isolated, but you are more isolated on an island, which could be why they developed a unique practice and culture.”