For all Earth’s roughly 4.5 billion year history, volcanic eruptions and plate tectonics have been shaping life–for better or worse. A volcanic eruption sometime around 2,900 BCE in what is now Northern Europe may have blocked out the sun and subsequently harmed the agriculture-depended Neolithic peoples living there. Now, climatological evidence indicates that some shale “sun stones” found in present-day Denmark likely were related to this cataclysmic volcanic eruption. The findings are detailed in a study published January 16 in the journal Antiquity.
Eruptions so large that they affect the weather on Earth have occurred numerous times in Earth’s history. In 43 BCE, a volcano in present day Alaska spewed so much sulphur into the air that Ancient Greek and Roman sources documented that harvests failed and famine and disease spread for years. Mount Tambora in Indonesia erupted in 1815 and led to the “year without a summer” in Europe and the United States, cooling temperatures for over three years and reducing crop yields.
While scientists do not have any similar written sources of eruptions from Neolithic times–about 10,000 to 2,000 BCE–they do have ice cores. These long time capsules that are brought up from glaciers can show millions of years of climate history.
In this new study, climate scientists analyzed ice cores from the Greenland ice sheet. They analyzed the rings on some bites of wood in the cores and found evidence of frost during the spring and summer months both before and after 2,900 BCE. The team could also see reduced radiation from the sun and consequent cooling. Both of these can be traced in parts of North America and Europe around this same time period.
That new climate data from the ice cores sheds new light on a group of unique archaeological artifacts called sun stones from the Vasagård site on the island of Bornholm in Denmark.
“We have known for a long time that the sun was the focal point for the early agricultural cultures we know of in Northern Europe,” study co-author and University of Copenhagen archeologist Rune Iversen said in a statement. “They farmed the land and depended on the sun to bring home the harvest. If the sun almost disappeared due to mist in the stratosphere for longer periods of time, it would have been extremely frightening for them.”
Several sun stones were found at the Vasagård West site in 2017. They are flat pieces of shale with engraving of the sun. The stones are believed to have symbolized fertility and may have been sacrificed to ensure sun and growth. The sun stones were put into ditches along with animal bones-belived to be the remains of ritual feasts–broken clay vessels, and flint objects sometime around 2,900 BCE. The ditches were then closed up with the sacrificial objects inside.
According to the team, there is a high chance that a connection exists between the volcanic eruption, the subsequent changes in climate, and the ritual sun stone sacrifices. In addition to a deteriorating climate, Northern European Neolithic cultures were also affected by the plague and a major shift in cultural traditions.
[ Related: The Aztecs’ solar calendar helped grow food for millions of people. ]
“It is reasonable to believe that the Neolithic people on Bornholm wanted to protect themselves from further deterioration of the climate by sacrificing sun stones,” said Iversen. “Or perhaps they wanted to show their gratitude that the sun had returned again.”
Four of the sun stones are slated to go on display at the The National Museum of Denmark in Copenhagen on January 28.
“The sunstones are completely unique, also in a European context,” Lasse Vilien Sørensen, a study co-author and senior researcher at The National Museum of Denmark, said in a statement. “The closest we get to a similar sun-cult in the Neolithic is some passage graves in southern Scandinavia or henge structures like Stonehenge in England, which some researchers associate with the sun.”
